WO2025190884A1

WO2025190884A1 - Metallocenes for the manufacture of propylene copolymers

Info

Publication number: WO2025190884A1
Application number: PCT/EP2025/056498
Authority: WO
Inventors: Luigi Maria Cristoforo RESCONI; Martin NEUHEIMER
Original assignee: Borealis GmbH
Current assignee: Borealis GmbH
Priority date: 2024-03-13
Filing date: 2025-03-10
Publication date: 2025-09-18
Anticipated expiration: 2026-09-13

Abstract

The disclosure relates to a process for producing a propylene copolymer resin, comprising polymerizing propylene and at least one C₄-C₁₀ alpha olefin comonomer and optionally ethylene in the presence of a polymerization catalyst comprising, (i) a metallocene complex of formula (I); (ii) a cocatalyst system comprising a cocatalyst comprising a group 13 element; and (iii) optionally a support; wherein the metallocene complex of formula (I) is (I), wherein Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently selected from C₁-C₂₀-hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form, together with the Si atom to which they are attached, a C₄-C₈ ring; R² and R^2'are each independently CH₂-R²¹, with R²¹ being H or C₁-₁₀-hydrocarbyl; n are each independently selected from an integer of from 1 to 5; each R³ and R⁴ is independently selected from H; C₁-C₁₀-hydrocarbyl; or -OR, -SR or -NR_2, where R is C₁-C₁₀ hydrocarbyl; and/or wherein two adjacent R³ or two adjacent R⁴form a ring together with the two C atoms of the phenyl ring to which they are bonded; R⁵ is C₁-C₁₀-hydrocarbyl, and R⁶ is OR⁸, where R⁸ is a C₁-C₁₀-hydrocarbyl; or R⁶ is OR⁹, wherein R⁵ and R⁹ form a C₃to C₇ carbocycle together with the O groups and two C atoms of the phenyl ring to which the O groups of -OR⁵ and -OR⁹ are bonded; R^5' is C₁-₁₀-hydrocarbyl and R^6' is OR^8', where R^8' is a C₁-C₁₀-hydrocarbyl; or R^6'is OR^9', wherein R^5' and R^9'form a C₃ to C₇carbocycle together with the O groups and two C atoms of the phenyl ring to which the O groups of -OR^5'and -OR⁹are bonded; and R⁷ is H, Me, OMe, or C₆-C₂₀-aryl, whereby the C₆-C₂₀-aryl is optionally substituted 1 to 5 times with R³, whereby at least one R³ per said aryl group is not H.

Description

METALLOCENES FOR THE MANUFACTURE OF PROPYLENE COPOLYMERS FIELD OF THE DISCLOSURE The present disclosure relates to the use of bisindenyl metallocene catalysts for the production of polypropylene copolymers, especially with ethylene and/or butene, in particular propylene- ethylene-butene terpolymers, having an excellent balance between high catalyst productivity and high copolymer molecular weight, and hence low MFR at high catalyst productivity even at relatively high comonomer content, therefore enabling the production of copolymers having both low MFR and low sealing initiation temperatures. BACKGROUND OF THE DISCLOSURE Metallocene catalysts have been used to manufacture polyolefins for many years. Countless academic and patent publications describe the use of these catalysts in olefin polymerization. Metallocenes are now used industrially and polyethylenes and polypropylenes in particular are often produced using cyclopentadienyl based catalyst systems with different substitution patterns. Metallocene catalysts have been used also in the production of propylene-butene copolymers and propylene-ethylene-butene terpolymers. These copolymers and terpolymers are used especially for films, for example for blown or cast films, and to produce the sealing layer of multilayer BOPP films. These copolymers and terpolymers must have specific MFR₂ values, such as MFR₂ between 0.5 and 3 for blown films, 8-10 for cast films, and MFR₂ matching that of the core hPP layer, typically MFR₂ between 6 and 8, in the case of the sealing layer of multilayer BOPP films. The main advantage in using metallocene catalysts for producing propylene-butene copolymers and propylene-ethylene-butene terpolymers is that metallocene catalysts have a much higher reactivity for higher olefins like 1-butene and 1-hexene compared to Ziegler-Natta catalysts. On the other hand, in such copolymerization with metallocene catalysts, the higher olefins tend to reduce the molecular weight of the copolymer, that is, increase its MFR₂. Therefore, the amount of hydrogen used in such processes needs to be reduced, but this in turn leads to reduced catalyst productivities. Solutions to this problem have been described, for example, in WO2019215122 and in EP20193414, in which a combination of two activators, namely methylaluminoxane and trityl tetrakis(pentafluorophenyl)borate, is used. WO2019179959 describes C₁-symmetric bisindenyl complexes comprising an indenyl moiety bearing 5-methoxy and 6-tert-butyl substituents and an indacenyl moiety bearing two aryl substituents on its 4,8 positions. The use of one of such metallocenes, formulated in silica catalysts containing both methylaluminoxane and trityl tetrakis(pentafluorophenyl)borate activators, has been described also for the production of propylene-butene copolymers in WO2023046573 and WO2023046824. It can sometimes be difficult to obtain high molecular weight e.g. propylene-butene copolymers and propylene-ethylene-butene terpolymers while maintaining desirable levels of catalyst productivity with such prior art catalysts. The present inventors thus sought to identify new metallocenes, which are able to provide high molecular weight e.g. propylene-butene copolymers and propylene-ethylene-butene terpolymers while maintaining desirable levels of catalyst productivity, especially in the case of the terpolymerization of propylene, in particular between propylene, butene, and ethylene. The desired catalysts should also have improved performance in high temperature polymerization, in particular in loop reactors. BRIEF DESCRIPTION OF THE DISCLOSURE An object of the present disclosure is to provide a new process for producing a propylene copolymer resin, comprising polymerizing propylene and at least one comonomer selected from ethylene and C4-C10 alpha olefin comonomers, that can be used to provide copolymer resins with sufficiently low MFR2 at desirable levels of productivity. The object of the disclosure is achieved by a process utilizing metallocene complexes of formula (I) which is characterized by what is stated in the independent claims. The preferred embodiments are disclosed in the dependent claims. It was surprisingly found that specific C1-symmetric metallocenes incorporating at least one alkoxy substituent on each indenyl ligand, in combination with specific substitution of the other ligand positions, provide desired properties. DEFINITIONS Throughout the description, the following definitions are employed: The term “C₁-C₂₀-hydrocarbyl” includes C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₂-C₂₀-alkynyl, C₃-C_20- cycloalkyl, C₃-C₂₀-cycloalkenyl, C₆-C₂₀-aryl, C₇-C_20-alkylaryl, and C₇-C₂₀-arylalkyl groups or, of course, mixtures of these groups, such as cycloalkyl substituted by alkyl. Unless otherwise stated, preferred C₁-C₂₀-hydrocarbyl groups are C₁-C₂₀-alkyl, C₄-C₂₀-cycloalkyl, C₅-C₂₀- cycloalkyl-alkyl groups, C₇-C₂₀-alkylaryl groups, C₇-C₂₀-arylalkyl groups, and C₆-C₂₀-aryl groups, especially C₁-C₁₀-alkyl groups, C₆-C₁₀-aryl groups, and C₇-C₁₂-arylalkyl groups, e.g. C₁-C₈-alkyl groups. Most especially preferred hydrocarbyl groups are methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, C₅-C₆-cycloalkyl, cyclohexylmethyl, phenyl, and benzyl. The term “C₁-C₁₀-hydrocarbyl” includes C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl, C₂-C₁₀-alkynyl, C₃-C₁₀- cycloalkyl, C3-C10-cycloalkenyl, C6-C10-aryl, C7-C10-alkylaryl, and C7-C10-arylalkyl groups or, of course, mixtures of these groups, such as cycloalkyl substituted by alkyl. Unless otherwise stated, preferred C₁-C₁₀-hydrocarbyl groups are C₁-C₁₀-alkyl, C₄-C₁₀-cycloalkyl, C₅-C₁₀- cycloalkyl-alkyl groups, C7-C10-alkylaryl groups, C7-C10-arylalkyl groups, and C6-C10-aryl groups, especially C1-C6-alkyl groups, C6-aryl groups, and C7-C10-arylalkyl groups, e.g. C1-C6- alkyl groups. Most especially preferred hydrocarbyl groups are methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, C5-C6-cycloalkyl, cyclohexylmethyl, phenyl, and benzyl. It is to be noted that linear and branched hydrocarbyl groups cannot contain cyclic units. Aliphatic hydrocarbyl groups cannot contain aryl rings. The term “heteroatoms of Group 14-16 of the Periodic Table” includes for example Si, N, O or S. The term “C4-C8-ring” as used herein refers to a cyclic group containing 4 to 8 carbon atoms. When the term “C4-C8-ring” is used herein in connection to R¹2Si<, it refers to a cyclic group containing 4 to 8 carbon atoms and a Si atom, and includes for example silacycloalkane groups, such as silacyclobutane, silacyclopentane, or 9-silafluorene. The numbering of these rings will be evident from the structures indicated herein. The term “alkoxy” as used herein refers to an alkyl-oxy-group, where the alkyl group is as defined herein, such as given in relation to the C1-C20-hydrocarbyl group above. Unless otherwise stated, it is preferred that the alkoxy group is C1-C10-alkoxy, more preferably C1-C6- alkoxy, especially methoxy or ethoxy. The term “halogen” includes fluoro, chloro, bromo, and iodo groups, especially chloro or fluoro groups, when relating to the complex definition. The oxidation state of the metal ion is governed primarily by the nature of the metal ion in question and the stability of the individual oxidation states of each metal ion. It is appreciated that in the complexes of the invention, the metal ion is coordinated by ligands X to satisfy the valence of the metal ion and to fill its available coordination sites. The nature of these sigma-ligands can vary greatly. Catalyst activity is defined in this application to be the amount of polymer produced/g catalyst/h. Metallocene is defined here to be the amount of polymer produced/g metallocene/h. The term productivity is also sometimes used to indicate the catalyst activity although herein it designates the amount of polymer produced per unit weight of catalyst. The term “molecular weight” is used herein to refer to weight average molecular weight Mw unless otherwise stated. The term “consisting essentially of” is used herein to refer to that further components may be present namely those not materially affecting the essential characteristics of the compound or composition e.g. minor amounts of impurities. DETAILED DESCRIPTION OF THE DISCLOSURE Polymerization The present invention relates to a process for producing a propylene copolymer resin, comprising polymerizing propylene and at least one C4-C10 alpha olefin comonomer and optionally ethylene in the presence of a polymerization catalyst comprising a specific metallocene catalyst comprising, preferably essentially consisting of, more preferably consisting of: (i) a metallocene complex of formula (I) as discussed herein; (ii) a cocatalyst system comprising a cocatalyst comprising a group 13 element; and (iii) optionally a support. The process for producing a propylene copolymer resin preferably comprises polymerizing propylene with either (a) ethylene and a C₄-C₁₀ alpha olefin comonomer or (b) at least two different C₄-C₁₀ alpha olefin comonomers. Details of the polymerization catalyst are discussed under section Polymerization catalyst. Polymerization in the process of the invention may be effected in one or more, e.g.1, 2, or 3, step(s). Preferably, the same polymerization catalyst is used in each step and ideally, it is transferred from pre-polymerization to subsequent polymerization steps in sequence in a well- known manner. Pre-polymerization The process of the invention may utilise an in-line pre-polymerization step. The in-line pre- polymerization step takes place just before the first polymerization step (I) and may be effected in the presence of hydrogen although the concentration of hydrogen should be low if it is present. The concentration of hydrogen may be from 0 to 1 mol(hydrogen)/ kmol(propylene), preferably from 0.001 to 0.1 mol(hydrogen)/kmol(propylene). The temperature conditions within the pre-polymerization step are ideally kept low such as 0 to 50°C, preferably 5 to 40°C, more preferably 10 to 30°C. The pre-polymerization stage preferably polymerizes propylene monomer only. The average (e.g. mean) residence time in the pre-polymerization reaction stage is short, typically 5 to 30 min. The pre-polymerization stage preferably generates less than 5 wt% of the total polymer formed, such as 3 wt% or less. Pre-polymerization preferably takes place in its own dedicated reactor, ideally in liquid propylene slurry. The prepolymerized catalyst is then transferred over to the first polymerization step. However, it is also possible, especially in batch processes, that pre- polymerization is carried out in the same reactor as the first polymerization step. Polymerization step(s) The present invention involves polymerizing propylene and at least one C4-C10 alpha olefin comonomer and optionally ethylene. The propylene may be copolymerized with either (a) ethylene and a C4-C10 alpha olefin comonomer or (b) at least two different C4-C10 alpha olefin comonomers. In one embodiment, propylene is polymerized with ethylene and 1-butene. The polymerization process may comprise one or more polymerization steps, provided that at least one polymerization step involves providing a propylene copolymer fraction, preferably a terpolymer fraction. Polymerization in the process of the invention may be effected in one or more, e.g.1, 2, or 3, polymerization reactors, using conventional polymerization techniques, e.g. gas phase, solution phase, slurry or bulk polymerization, or combinations thereof, like a combination of a slurry and at least one gas phase reactor. In an embodiment the process comprises the step of (I) polymerizing propylene and at least one C₄-C₁₀ alpha olefin comonomer and optionally ethylene, preferably (a) a C₄-C₁₀ alpha olefin comonomer and ethylene or (b) at least two different C₄-C₁₀ alpha olefin comonomers, in a slurry reactor to produce a propylene terpolymer. In said embodiment the process is carried out in at least one slurry reactor. Where a slurry polymerization reactor is employed, this is typically effected in at least one loop reactor. Ideally, the polymerization takes place in bulk, i.e. in a medium of liquid propylene. For slurry reactors in general and in particular for bulk reactors, the reaction temperature will generally be in the range 60 to 100^C, preferably 70 to 85°C. The reactor pressure will generally be in the range 5 to 80 bar-g (e.g.20 to 60 bar-g), and the average (e.g. mean) residence time will generally be in the range 0.1 to 5 hours (e.g.0.3 to 2 hours). It is preferred that hydrogen is used in the polymerization step. The amount of hydrogen employed is typically considerably larger than the amount used in the prepolymerization stage. Multistage polymerization process Preferably, the propylene copolymer (e.g. propylene terpolymer) resin is produced in a multistage process comprising at least two reactors connected in series. In an example, the present process is a multistage polymerization process, said process comprising an optional but preferred pre-polymerization step, followed by a first, and a second polymerization step. At least one of the polymerization steps in the multistage polymerization process may be carried out in a gas phase reactor. One preferred process configuration is based on a Borstar^® type cascade. Accordingly, in a further embodiment the process comprises (I) polymerizing in at least one slurry reactor propylene and at least one C4-C10 alpha olefin comonomer and optionally ethylene, preferably propylene and either (a) ethylene and a C4-C10 alpha olefin comonomer or (b) at least two different C4-C10 alpha olefin comonomers, more preferably propylene, at least one C4-C10 alpha olefin comonomer and ethylene, in a slurry reactor to produce a propylene copolymer in 50 to 99 wt% of the total weight of the propylene copolymer resin end product, and the process further comprises the step of (II) transferring the reaction mixture of step (I) into a gas phase reactor for producing propylene copolymer amounting to 1 to 50 wt% of the propylene copolymer resin end product. Preferably, the process comprises (I) polymerizing in at least one slurry reactor propylene, ethylene and a C₄-C₁₀ alpha olefin comonomer, more preferably propylene, ethylene and butene, in a slurry reactor to produce a propylene terpolymer in 50 to 99 wt% of the total weight of the propylene terpolymer resin end product, and the process further comprises the step of (II) transferring the reaction mixture of step (I) into a gas phase reactor for producing propylene terpolymer amounting to 1 to 50 wt% of the propylene terpolymer resin end product. In an example a) of a multistage process the present process for the preparation of a propylene terpolymer resin, comprises: (I’) in a first polymerization step, preferably in at least one slurry reactor, polymerizing propylene and at least one C4-C10 alpha olefin comonomer and optionally ethylene, preferably polymerizing propylene and butene, in the presence of the polymerization catalyst to produce a propylene copolymer matrix (A); and subsequently (II’) in a second polymerization step, preferably in at least one gas phase reactor, polymerizing propylene and at least one comonomer selected from ethylene and C4-C10 alpha olefin comonomers, preferably at least two different comonomers selected from ethylene and C4-C10 alpha olefin comonomers, more preferably ethylene and at least one C4-C10 alpha olefin comonomer, such as butene, in the presence of the polymerization catalyst and the propylene copolymer matrix (A) from step (I) to produce a propylene copolymer (e.g. propylene terpolymer) phase (B) dispersed in the propylene copolymer matrix (A) e.g. to provide the propylene copolymer, preferably, propylene terpolymer resin. Preferably in said preferred example a) the propylene copolymer matrix (A) produced in step (I’) is produced in an amount of less than or equal to 90 wt %, and b) the propylene terpolymer phase (B) produced in step (II”) is produced in an amount of more than or equal to 10 wt %,of the total weight of the produced propylene terpolymer resin. First polymerization step (I) –propylene copolymer matrix phase production In an embodiment the present invention, the first polymerization step involves polymerizing propylene and at least one C₄-C₁₀ alpha olefin comonomer. In this embodiment, the comonomer polymerized with the propylene may be ethylene or a C₄-C₁₀ alpha olefin comonomer or a mixture of comonomers might be used such as a mixture of ethylene and a C₄-C₁₀ alpha olefin comonomer. As comonomers to propylene are preferably used ethylene, 1-butene, 1-hexene, 1-octene or any mixtures thereof, preferably ethylene. When ethylene comonomer is present in the polymer produced in the first polymerization step (I), its content may be up to 5 mol%, or 3.4 wt%, while when butene comonomer is present, then its content can be up to 5 mol%, or 6.6 wt%, provided that their combined content is at most 5 mol%, relative to the polymer as a whole. The first polymerization step may take place in any suitable reactor or series of reactors. The first polymerization step may take place in a slurry polymerization reactor such as a loop reactor or in a gas phase polymerization reactor, or a combination thereof. When the first polymerization step takes place in a loop reactor, then typically the reaction temperature is greater than 60^C, preferably greater than 65^C, more preferably greater than greater than 70^C. For example, the reaction temperature is than 65 to 85^C, such as 65 to 75^C, more preferably 70 to 75^C. Where a slurry polymerization reactor is employed, this is typically effected in at least one loop reactor. Ideally, the polymerization takes place in bulk, i.e. in a medium of liquid propylene. For slurry reactors in general and in particular for bulk reactors, the reaction temperature will generally be in the range of 60 to 80^C, preferably 65 to 75°C. The reactor pressure will generally be in the range 5 to 80 bar (e.g.20 to 60 bar), and the average (e.g. mean) residence time will generally be in the range 0.1 to 5 hours (e.g. 0.3 to 2 hours). When a gas phase reactor is employed, the reaction temperature will generally be in the range of 60 to 100°C, preferably 70 to 90°C. The reactor pressure will generally be in the range 10 to 35 bar (e.g. 15 to 30 bar), and the average (e.g. mean) residence time will generally be in the range 0.5 to 5 hours (e.g.1 to 2 hours). In a preferred embodiment, the first polymerization step takes place in a slurry loop reactor connected in cascade to a gas phase reactor. In such scenarios, the polymer produced in the loop reactor is transferred into the first gas phase reactor. It is preferred if hydrogen is used in the first polymerization step. The amount of hydrogen employed is typically considerably larger than the amount used in the prepolymerization stage. Second polymerization step (II) – gas phase production The second polymerization step (II) of the process of the invention may be a gas phase polymerization step in which propylene and, preferably, at least two different comonomers selected from ethylene and C₄-C₁₀ alpha olefin comonomers are polymerized in the presence of the polymerization catalyst and polymer from step (I). This polymerization step takes place in at least one gas phase reactor, optionally in the presence of an inert gas such as propane. Thus, the second polymerization step may take place in a single gas phase reactor or more than one gas phase reactor connected in series or parallel. The C₄-C₁₀ alpha olefin comonomer(s) may be, for example, 1-butene, 1-hexene, 1-octene or any mixtures thereof. Preferably, step (II) involves the polymerization of propylene, ethylene and butene. In the process of the invention, the temperature in the gas phase reactor will generally be in the range of 60 to 120°C, preferably in the range of 65 and 110^C, more preferably in the range of 65 and 100°C, more preferably in the range of 70 to 90°C. Higher gas phase reactor temperatures will favour e.g. higher levels of productivity and, in some embodiments, comonomer (e.g. ethylene) reactivity. In the process of the invention, the reactor pressure is at least 10 bar, preferably at least 15 bar, more preferably at least 16 bar, typically in the range of 10 to 60 bar, preferably in the range of 15 to 50 bar. The average (e.g. mean) residence time within any gas phase reactor will generally be 0.5 to 8 hours (e.g.0.5 to 4 hours). The gas used will be the monomer mixture optionally as mixture with a non-reactive gas such as propane. The hydrogen content within the gas phase reactor(s) is important for controlling polymer properties but is independent of the hydrogen added to prepolymerization and first polymerization steps. The production ratio or split (by weight) between the first and second polymerization steps is ideally 55:45 to 90:10. preferably 55:45 to 87:13, preferably 60:40 to 85:15. Note that any small amount of polymer formed in prepolymerization is counted as part of the polymer prepared in the first polymerization step. Polymerization catalyst The processes of the invention employs a polymerization catalyst comprising, preferably essentially consisting of, more preferably consisting of (i) a metallocene complex of formula (I); (ii) a cocatalyst system comprising a cocatalyst comprising a group 13 element; and (iii) optionally a support. Metallocene catalyst complexes For the purpose of this invention, racemic-anti means that the two indenyl ligands are oriented in opposite directions with respect to the cyclopentadienyl-metal-cyclopentadienyl plane, while racemic-syn means that the two indenyl ligands are oriented in the same direction with respect to the cyclopentadienyl-metal-cyclopentadienyl plane, as shown in the scheme below. Racemic Anti Racemic Syn In the present invention, formula (I), and any sub formulae, are intended to cover both syn- and anti-configurations. Preferred metallocene catalyst complexes are in the anti- configuration. The metallocene complexes of the invention are preferably employed as the racemic-anti- isomers. Ideally, therefore at least 95% mol, such as at least 98 %mol, especially at least 99 %mol of the metallocene catalyst complex is in the racemic anti-isomeric form. The present metallocene catalyst complexes require the combination of three distinctive features of the ligand framework: 1: each indenyl group has an aryl group at the 4-position, 2: a hydrocarbyloxy moiety at the 5-position of each indenyl group, preferably a 5-alkoxy group (e.g.5-methoxy group) or a 5,6-dioxoalkylene ring, and 3: at least one alkyl substituent on the 2-position of each indenyl group. The present metallocene catalyst complexes are also distinctive in having a hydrocarbyloxy moiety at the 6-position of each indenyl group. The present invention accordingly utilizes metallocene complexes of formula (I) (I) wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently selected from C₁-C₂₀-hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form, together with the Si atom to which they are attached, a C₄-C₈-ring; R² and R²’ are each independently CH₂-R²¹, with R²¹ being H or C₁-C₁₀-hydrocarbyl; n are each independently selected from an integer of from 1 to 5; each R³ and R⁴ is independently selected from H; C₁-C₁₀-hydrocarbyl; or -OR, -SR or -NR₂, where R is C₁-C₁₀-hydrocarbyl; and/or wherein two adjacent R³ groups or two adjacent R⁴ groups form a ring together with the two C atoms of the phenyl ring to which they are bonded; R⁵ is C₁-C₁₀-hydrocarbyl, and R⁶ is OR⁸, where R⁸ is a C₁-C₁₀-hydrocarbyl; or R⁶ is OR⁹, wherein R⁵ and R⁹ form a C₃ to C₇ carbocycle together with the O groups and two C atoms of the phenyl ring to which the O groups of -OR⁵ and -OR⁹ are bonded; R⁵’ is C1-C10-hydrocarbyl and R⁶’ is OR⁸’, where R⁸’ is a C1-C10-hydrocarbyl; or R⁶’ is OR⁹’, wherein R⁵’ and R⁹’ form a C₃ to C₇ carbocycle together with the O groups and two C atoms of the phenyl ring to which the O groups of -OR⁵’ and -OR⁹’ are bonded; and R⁷ is H, Me, OMe, or C6-C20-aryl, whereby the C6-C20-aryl is optionally substituted 1 to 5 times with R³, whereby at least one R³ per said aryl group is not H. For the above-defined metallocene complexes of formula (I), the following represent preferable embodiments, which can be selected alone or in combination: In a complex of formula (I) it is preferred if Mt is Zr or Hf, preferably Zr. Each X is a sigma ligand. Preferably, each X is independently, same or different from each other, H, halogen, C₁-C₆-alkoxy, or R´ group, where R´ is C_1-C₆-alkyl, phenyl, or benzyl. More preferably, each X is independently, same or different from each other, Cl, benzyl, or methyl. It is preferred that both X groups are the same. Most preferably both X are Cl, methyl, or benzyl, especially Cl. Preferably R¹ are each independently, same or different from each other, C1-C10-hydrocarbyl, more preferably C1-C10-alkyl, C4-C10-cycloalkyl, C5-C10-cycloalkyl-alkyl, C7-C10-arylalkyl, C6-C10-aryl, or C7-C10-alkylaryl, such as methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, C3- C8-cycloalkyl, cyclohexylmethyl, phenyl, or benzyl, even more preferably both are C1-C6-alkyl, C5-C6-cycloalkyl, or C6-aryl. In an embodiment each R¹ is independently, same or different from each other, C1-C10-alkyl or C1-C6-alkyl, optionally substituted with C1-C10-alkoxy. It is preferred that both R¹ groups are the same. Most preferably, both R¹ are methyl. Preferably, R¹ are each independently, same or different from each other, C1-C6-alkyl, more preferably methyl. Preferably R² and R²’ are each independently, same or different from each other, CH2-R²¹, with R²¹ being H, C1-C6-alkyl, or C3-C8-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n- butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. More preferably R²¹ is H, linear C1-C3-alkyl, or branched C3-alkyl. R²¹ is preferably H, linear C1-C6-alkyl or branched C3-C6-alkyl, more preferably, R²¹ is H, C1-C3-alkyl or branched C3-alkyl. R²¹ is more preferably H or methyl. It is further preferred that R² is methyl or ethyl. Most preferably, R² is methyl or ethyl and R²’ is methyl or ethyl. In some embodiments, R² and R²’ are independently methyl or ethyl. R² and R²’ may be both methyl or both ethyl. Advantageously, R² and R²’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H or C₁-C₆-alkyl; preferably H or linear C₁-C₆-alkyl, more preferably H or linear C₁-C₄-alkyl; preferably H, methyl or ethyl. In some embodiments, one of R² and R²’ is methyl, and the other is of the formula CH₂-R²¹, with R²¹ being C₁-C₆-alkyl. In such embodiments, the R²¹ of the R² and R²’ that is not methyl is preferably C₁-C₄-alkyl; more preferably linear C₁-C₄-alkyl, even more preferably methyl or ethyl. In some embodiments, R² is methyl, and R²’ is of the formula CH₂-R²¹, with R²¹ being C₁-C₆-alkyl. In such embodiments, the R²¹ of R²’ is preferably C₁-C₄-alkyl; more preferably linear C₁-C₄-alkyl, even more preferably methyl or ethyl. In a preferred embodiment, R² is methyl or ethyl and R²’ is methyl or ethyl. In more preferred embodiments, R² and R²’ are independently methyl or ethyl. Most preferably, R² and R²’ are both methyl or both ethyl. Two adjacent R³ or two adjacent R⁴ form a ring together with the two C atoms of the phenyl ring to which they are bonded. The ring is preferably a C4-C8-ring, more preferably a C5-C6-ring, even more preferably a C6-ring. Preferably R³ and R⁴ are each independently, same or different from each other, H, C1-C6-alkyl, or C6-C20-aryl, more preferably H, C1-C4-alkyl, or -OR³¹, with R³¹ being a C1-C4-hydrocarbyl. Even more preferably, each R³ and R⁴ are each independently, same or different from each other, H, methyl, ethyl, isopropyl, tert-butyl, or methoxy, especially H, methyl, or tert-butyl, whereby at least one R³ per phenyl group, for example, two R³ per phenyl group and at least one R⁴, for example, two R⁴ per phenyl group is not H. Furthermore, it is possible that each of the phenyl rings have the same substitution pattern or that the phenyl rings have different substitution patterns. It is preferred that one or two R³ and/or R⁴ groups is H. If two R³ and/or R⁴ groups are H then the remaining R³ and/or R⁴ group, respectively, is preferably in the para position. If one R³ and/or R⁴ group is H then the remaining R³ and/or R⁴ groups are preferably in the meta positions. Advantageously one or two R³ is H, more preferably, one R³ is H. The remaining R³ may be the same, like 3´,5´-di-methyl. Alternatively, only one R³ is not H, for example, 4´-tert-butyl. Advantageously, one or two R⁴ is H, more preferably one R⁴ is H. The remaining two R⁴ may be the same like 3´,5´-di-methyl or 3´,5´-di-tert-butyl. In one embodiment, two R³ are not H and are C₁-C₆-alkyl, preferably methyl, and two R⁴ are not H and these two R⁴ are C₁-C₆ alkyl, preferably methyl. Preferably, the two R³ and/or two R⁴ that are not H (e.g. methyl) are in the 3, 5-positions. R⁵ may be C₁-C₁₀-hydrocarbyl, and R⁶ may be OR⁸, where R⁸ is a C₁-C₁₀-hydrocarbyl. Where R⁵ is C₁-C₁₀-hydrocarbyl, R⁵ may be linear C₁-C₆-alkyl, branched C₃-C₆-alkyl, or C_3-C₈ cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. More preferably, R⁵ may be methyl or ethyl, yet more preferably methyl. Where R⁸ is a C₁-C₁₀-hydrocarbyl, R⁸ may be linear C₁-C₆-alkyl, branched C₃-C₆-alkyl, or C_3- C8 cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. Alternatively, R⁶ may be OR⁹, wherein R⁵ and R⁹ form a C3 to C7 carbocycle together with the O groups of -OR⁵ and -OR⁹ and two C atoms of the phenyl ring to which the O groups of -OR⁵ and -OR⁹ are bonded. The carbocycle may be a C4 carbocycle. Here, R⁵, R⁹, the two O groups of -OR⁵ and -OR⁹ and the two carbon atoms of the phenyl ring to which the O groups of -OR⁵ and -OR⁹ are bonded form a 6-membered ring. The carbocycle may be substituted, for example, with one or more C1 to C3 alkyl groups, or preferably unsubstituted. R⁵’ may be C1-C10-hydrocarbyl, and R⁶’ may be OR⁸’, where R⁸’ is a C1-C10-hydrocarbyl. Where R⁵’ is C1-C10-hydrocarbyl, R⁵’ may be linear C1-C6-alkyl, branched C3-C6-alkyl, or C3- C8-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. More preferably, R⁵’ may be methyl or ethyl, yet more preferably methyl. Where R⁸’ is a C1-C10-hydrocarbyl, R⁸’ may be linear C1-C6-alkyl, branched C3-C6-alkyl, or C3-C8-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. Alternatively, R⁶’ may be OR⁹’, wherein R⁵’ and R⁹’ form a C₃ to C₇ carbocycle together with the O groups of -OR⁵’ and -OR⁹’ and two C atoms of the phenyl ring to which the O groups of -OR⁵’ and -OR⁹’ are bonded. The carbocycle may be a C₄ carbocycle. Here, R⁵’, R⁹’, the two O groups of -OR⁵’ and -OR⁹’ and the two carbon atoms of the phenyl ring to which the O groups of -OR⁵’ and -OR⁹’ are bonded form a 6-membered ring. The carbocycle may be substituted, for example, with one or more C₁-C₃-alkyl groups, or preferably unsubstituted. Preferably, R⁵’ may be the same as R⁵. Preferably, R⁶ may be the same as R⁶’. More preferably, R⁵’ may be the same as R⁵, and R⁶ may be the same as R⁶’. R⁷ is H, Me, OMe, or C₆-C₂₀-aryl, whereby C₆-C₂₀-aryl is optionally substituted 1 to 5 times with R³, whereby at least one R³ per said aryl group is not H. As mentioned above, preferably R³ is H, C₁-C₆-alkyl, or C₆-C₂₀-aryl, more preferably H, C₁-C₄-alkyl, or -OR³¹, with R³¹ being a C₁-C₄-hydrocarbyl. Even more preferably, R³ is H, methyl, ethyl, isopropyl, tert-butyl, or methoxy, especially H, methyl, or tert-butyl, whereby at least one R³ per phenyl group, for example, two R³ per phenyl group is not H. Where R⁷ is a C6-C20-aryl being substituted 1 to 5 times with R³, it is preferred that one or two R³ groups is H. If two R³ groups is H then the remaining R³ is preferably in the para position. If one R³ is H then the remaining R³ groups are preferably in the meta positions. Advantageously one or two R³ is H, more preferably, one R³ is H. The remaining R³ may be the same, like 3´,5´-di-methyl. Alternatively, only one R³ is not H, for example, 4´-tert-butyl. In one embodiment, two R³ are not H and are C1-C6-alkyl, preferably methyl. Preferably, the two R³ that are not H (e.g. methyl) are in the 3,5-positions. Preferably R⁷ is H. Viewed from another aspect the invention utilizes a metallocene catalyst complex of formula (I-a): (I-a) wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently, same or different from each other, C1-C20-hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form, together with the Si atom they are attached to, a C4-C8 ring; R² and R²’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H or C₁-C₁₀-hydrocarbyl; R³ and R⁴ are each independently, same or different from each other, H, linear or branched C₁-C₆-alkyl, C₇-C₂₀-arylalkyl, C₇-C₂₀-alkylaryl, C₆-C₂₀-aryl, or -OR³¹, with R³¹ being C1-C10-hydrocarbyl, whereby at least one R³ per present phenyl group and at least one R⁴ is not H; m are each independently, same or different from each other, an integer from 2 to 4; each R⁶¹ is independently, same or different from each other, -CH2-, -CHR*-, or -C(R*)2- group, with R* being C1-C2-alkyl; R⁷ is H, Me, OMe, or C6-C20-aryl, whereby C6-C20-aryl is optionally substituted 1 to 5 times with R^3, whereby at least one R³ per said aryl group is not H. Each of the definitions for Mt, X, R¹, R², R²’, R³, R⁴ and R⁷ described herein for the metallocene complex of formula (I) also applies to the metallocene complex of formula (I-a), unless the context indicates otherwise. For the above-defined metallocene complexes of formula (I-a), the following represent preferable embodiments, which can be selected alone or in combination: m are each independently, same or different from each other, an integer from 2 to 4, preferably 2. Each R⁶¹ is independently, same or different from each other, -CH2-, -CHR*-, or -C(R*)2- group, with R* being C1-C2-alkyl, preferably C1-alkyl. Preferably, each R⁶¹ is -CH2-. Viewed from another aspect the invention utilizes a metallocene catalyst complex of formula (I-b)

(I-b) wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently, same or different from each other, C₁-C₂₀-hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form together with the Si atom they are attached to a C₄-C₈ ring; R² and R²’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H or C₁-C₁₀-hydrocarbyl; R³ and R⁴ are each independently, same or different from each other, H, linear or branched C₁-C₆-alkyl, C₇-C₂₀-arylalkyl, C₇-C₂₀-alkylaryl, C₆-C₂₀-aryl, or -OR³¹, with R³¹ being C₁-C₁₀-hydrocarbyl, whereby at least one R³ and at least one R⁴ is not H; m are each independently, same or different from each other, an integer from 2 to 4; each R⁶¹ is independently, same or different from each other, -CH₂-, -CHR*-, or -C(R*)-, with R* being C₁-C₂-alkyl. Each of the definitions for Mt, X, R¹, R², R²’, R³ and R⁴ described herein for the metallocene complex of formula (I) also applies to the metallocene complex of formula (I-b), unless the context indicates otherwise. Furthermore, each of the definitions for R⁶¹ and m described herein for the metallocene complex of formula (I-a) also applies to the metallocene complex of formula (I-b), unless the context indicates otherwise. Viewed from another aspect the invention utilizes a metallocene catalyst complex of formula (I-c): (I-c) wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently, same or different from each other, C1-C20-hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form together with the Si atom they are attached to a C₄-C₈ ring; R² and R²’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H or linear or branched C_1-6-alkyl; R³ and R⁴ are each independently, same or different from each other, H, linear or branched C₁-C₆-alkyl, C₇-C₂₀-arylalkyl, C₇-C₂₀-alkylaryl, C₆-C₂₀-aryl, or -OR³¹, with R³¹ being C₁-C₁₀-hydrocarbyl, whereby at least one R³ and at least one R⁴ is not H. Each of the definitions for Mt, X, R¹, R², R²’, R³ and R⁴ described herein for the metallocene complex of formula (I) also applies to the metallocene complex of formula (I-c), unless the context indicates otherwise.

Viewed from another aspect the invention utilizes a metallocene catalyst complex of formula (I-d): (I-d) In a complex of formula (I-d) it is preferred if Mt is Zr or Hf, preferably Zr. Each X is a sigma ligand. Preferably, each X is independently, same or different from each other, H, halogen, C1-C6-alkoxy, or R´ group, where R´ is C1-C6-alkyl, phenyl, or benzyl. More preferably, each X is independently, same or different from each other, Cl, benzyl, or methyl. It is preferred that both X groups are the same. Most preferably both X are Cl, methyl, or benzyl, especially Cl. Preferably R¹ are each independently, same or different from each other, C₁-C₁₀-hydrocarbyl, more preferably C₁-C₁₀-alkyl, C₄-C₁₀-cycloalkyl, C₅-C₁₀-cycloalkyl-alkyl, C₇-C₁₀-arylalkyl, C₆-C₁₀-aryl, or C₇-C₁₀-alkylaryl, such as methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, C₃-C₈-cycloalkyl, cyclohexylmethyl, phenyl, or benzyl, even more preferably both are C₁-C₆-alkyl, C₅-C₆-cycloalkyl, or C₆-aryl. In an embodiment each R¹ is independently, same or different from each other, C₁-C₁₀-alkyl, optionally substituted with C₁-C₁₀-alkoxy. It is preferred that both R¹ groups are the same. Most preferably, both R¹ are methyl. Preferably R² and R^2’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H, C₁-C₆-alkyl, or C₃-C₈-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n- butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. More preferably R²¹ is H, linear C₁-C₃-alkyl, or branched C₃-alkyl. R²¹ is preferably H, linear C₁-C₆-alkyl or branched C₃-C₆-alkyl, more preferably, R²¹ is H, C₁-C₃-alkyl or branched C₃-alkyl. R²¹ is more preferably H or methyl. It is further preferred that R² is methyl or ethyl. Most preferably, R² is methyl or ethyl and R^2’ is methyl or ethyl. In some embodiments, R² and R^2’ are independently methyl or ethyl. R² and R^2’ may be both methyl or both ethyl. Advantageously, R² and R²’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H or C₁-C₆-alkyl; preferably H or linear C₁-C₆-alkyl, more preferably H or linear C1-C4 alkyl; preferably H, methyl or ethyl. In some embodiments, one of R² and R²’ is methyl, and the other is of the formula CH₂-R²¹, with R²¹ being C1-C6-alkyl. In such embodiments, the R²¹ of the R² and R^2’ that is not methyl is preferably C1-C4-alkyl; more preferably linear C1-C4-alkyl, even more preferably methyl or ethyl. In some embodiments, R² is methyl, and R²’ is of the formula CH2-R²¹, with R²¹ being C1-C6-alkyl. In such embodiments, the R²¹ of R^2’ is preferably C1-C4-alkyl; more preferably linear C1-C4-alkyl, even more preferably methyl or ethyl. In a preferred embodiment, R² is methyl or ethyl and R^2’ is methyl or ethyl. In more preferred embodiments, R² and R²’ are independently methyl or ethyl. Most preferably, R² and R²’ are both methyl or both ethyl. Preferably R³ and R⁴ are each independently, same or different from each other, H, C1-C6-alkyl, or C6-C20-aryl, more preferably H, C1-C4-alkyl, or -OR³¹, with R³¹ being a C1-C4-hydrocarbyl. Even more preferably, each R³ and R⁴ are each independently, same or different from each other, H, methyl, ethyl, isopropyl, tert-butyl, or methoxy, especially H, methyl, or tert-butyl, whereby at least one R³ per phenyl group, for example, two R³ per phenyl group and at least one R⁴, for example, two R⁴ per phenyl group is not H. Furthermore, it is possible that each of the phenyl rings have the same substitution pattern or that the phenyl rings have different substitution patterns. It is preferred that one or two R³ and/or R⁴ groups is H. If two R³ and/or R⁴ groups are H then the remaining R³ and/or R⁴ group, respectively, is preferably in the para position. If one R³ and/or R⁴ group is H then the remaining R³ and/or R⁴ groups are preferably in the meta positions. Advantageously one or two R³ is H, more preferably, one R³ is H. The remaining R³ may be the same, like 3´,5´-di-methyl. Alternatively, only one R³ is not H, for example, 4´-tert-butyl. Advantageously, one or two R⁴ is H, more preferably one R⁴ is H. The remaining two R⁴ may be the same like 3´,5´-di-methyl or 3´,5´-di-tert-butyl_. In one embodiment, two R³ are not H and are C₁-C₆-alkyl, preferably methyl, and two R⁴ are not H and these two R⁴ are C1-C6 alkyl, preferably methyl. Preferably, the two R³ and/or two R⁴ that are not H (e.g. methyl) are in the 3, 5– positions. R⁵ may be C1-C10-hydrocarbyl, and R⁶ may be OR⁸, where R⁸ is a C1-C10-hydrocarbyl. Where R⁵ is C1-C10-hydrocarbyl, R⁵ may be linear C1-C6-alkyl, branched C3-C6-alkyl, or C3-C8 cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. More preferably, R⁵ may be methyl or ethyl, yet more preferably methyl. Where R⁸ is a C1-C10-hydrocarbyl, R⁸ may be linear C1-C6-alkyl, branched C3-C6-alkyl, or C3-C8-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. R⁵’ may be C1-C10-hydrocarbyl, and R⁶’ may be OR⁸’, where R⁸’ is a C1-C10-hydrocarbyl. Where R⁵’ is C1-C10-hydrocarbyl, R⁵’ may be linear C1-C6-alkyl, branched C3-C6-alkyl, or C3- C8-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. More preferably, R⁵’ may be methyl or ethyl, yet more preferably methyl. Where R⁸’ is a C1-C10-hydrocarbyl, R⁸’ may be linear C1-C6-alkyl, branched C3-C6-alkyl, or C3-C8-cycloalkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, or cyclohexyl. Preferably, R⁵’ may be the same as R⁵. Preferably, R⁶ may be the same as R⁶’. More preferably, R⁵’ may be the same as R⁵, and R⁶ may be the same as R⁶’. In a preferred embodiment, R⁵ may be methyl or ethyl, yet more preferably methyl, and R⁵’ may be methyl or ethyl, yet more preferably methyl. In a more preferred embodiment, R⁵ and R⁵’ is methyl. R⁷ is H, Me, OMe, or C₆-C₂₀-aryl, whereby C₆-C₂₀-aryl is optionally substituted 1 to 5 times with R³, whereby at least one R³ per said aryl group is not H. As mentioned above, preferably R³ is H, C₁-C₆-alkyl, or C₆-C₂₀-aryl, more preferably H, C₁-C₄-alkyl, or -OR³¹, with R³¹ being a C₁-C₄-hydrocarbyl. Even more preferably, R³ is H, methyl, ethyl, isopropyl, tert-butyl, or methoxy, especially H, methyl, or tert-butyl, whereby at least one R³ per phenyl group, for example, two R³ per phenyl group is not H. Where R⁷ is a C₆-C₂₀-aryl being substituted 1 to 5 times with R³, it is preferred that one or two R³ groups is H. If two R³ groups is H then the remaining R³ is preferably in the para position. If one R³ is H then the remaining R³ groups are preferably in the meta positions. Advantageously one or two R³ is H, more preferably, one R³ is H. The remaining R³ may be the same, like 3´,5´-di-methyl. Alternatively, only one R³ is not H, for example, 4´-tert-butyl. In one embodiment, two R³ are not H and are C₁-C₆-alkyl, preferably methyl. Preferably, the two R³ that are not H (e.g. methyl) are in the 3,5-positions. Preferably R⁷ is H. Viewed from another aspect the invention utilizes a metallocene catalyst complex of formula Each of the definitions for Mt, X, R¹, R², R³, R⁴, R⁵ and R⁶ described herein for the metallocene complex of formula (I) or formula (I-d) also applies to the metallocene complex of formula (I-e), unless the context indicates otherwise. Preferably the metallocene complex of formula (I-e) is C₂-symmetric. For the metallocene complex of formula (I-e), preferably R⁵ is a C1-C3-alkyl. The metallocene catalyst complexes of the invention, including the metallocene complexes of formulas (I), (I-a), (I-b), (I-c) and (I-d), are preferably symmetrical, more preferably C2- symmetric. Symmetrical means simply that the two ligands forming the metallocene are the same, that is, each ligand bears a set of substituents that are chemically identical. The metallocene complexes of the invention are preferably chiral, racemic, bridged bisindenyl C₁-symmetric metallocenes in their anti-configuration. Although the complexes of the invention are formally C₁-symmetric, the complexes ideally retain a pseudo-C₂-symmetry since they maintain C2-symmetry in close proximity of the metal center although not at the ligand periphery. By nature of their chemistry both anti and syn enantiomer pairs (in case of C₁- symmetric complexes) are formed during the synthesis of the complexes. Preferably the metallocene complexes of the invention are preferably chiral, racemic, bridged bisindenyl C2-symmetric metallocenes in their anti-configuration. Preferred metallocenes are selected from: dimethylsilanediyl-bis[9-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-indeno[5,6- b][1,4]dioxin-6-yl]zirconium dichloride; and dimethylsilanediyl-bis[9-(3,5-dimethylphenyl)-7-ethyl-2,3-dihydro-indeno[5,6- b][1,4]dioxin-6-yl]zirconium dichloride. Cocatalyst To form active catalytic species it is normally necessary to employ a cocatalyst as is well known in the art. Cocatalysts comprising one or more compounds of Group 13 metals, like organoaluminium, organoboron, and/or borate compounds used to activate metallocene catalysts are suitable for use in this invention. In some examples, organoboron and/or borate compounds are not used. According to the present invention a cocatalyst system comprising an aluminoxane cocatalyst and optionally a boron containing cocatalyst is advantageously used in combination with the above defined metallocene catalyst complex. Preferably only cocatalysts comprising aluminium, like organoaluminium compounds used to activate metallocene catalysts, are utilized in this invention. In a preferred aspect of the present invention a cocatalyst system essentially consisting of, preferably consisting of, an aluminoxane cocatalyst is advantageously used in combination with the above defined metallocene catalyst complex. Thus, preferably no further cocatalysts comprising one or more compounds of Group 13 metals other than aluminium, like organoboron and/or borate compounds, used to activate metallocene catalysts are comprised in the polymerization catalyst. Suitable amounts of cocatalyst will be well known to the person skilled in the art. Preferably, the amount of cocatalyst is chosen to reach below defined molar ratios. The molar ratio of Al from the aluminoxane to the metal ion (Mt) (preferably zirconium) of the metallocene Al/Mt may be in the range 10:1 to 2000:1 mol/mol, preferably 50:1 to 1000:1, and more preferably 100:1 to 600:1 mol/mol. When a boron cocatalyst is used, the molar ratio of boron (B) to the metal ion (Mt) (preferably zirconium) of the metallocene B/Mt may be in the range 0.1:1 to 10:1 mol/mol, preferably 0.3:1 to 7:1, especially 0.5:1 to 3:1 mol/mol. Even more preferably, the molar ratio of feed amounts of boron (B) to metal ion (Mt), preferably zirconium, of the metallocene B/Mt is from 0.5:1 to 2:1 Aluminoxane cocatalyst The aluminoxane cocatalyst can be one of formula (A): where n is usually from 6 to 20 and R has the meaning below. Aluminoxanes are formed on partial hydrolysis of organoaluminum compounds, for example those of the formula AlR3, AlR2Y and Al2R3Y3 where R can be, for example, C1-C10-alkyl, preferably C1-C5-alkyl, or C3-C10-cycloalkyl, C7-C12-arylalkyl or -alkylaryl and/or phenyl or naphthyl, and where Y can be hydrogen, halogen, preferably chlorine or bromine, or C1-C10-alkoxy, preferably methoxy or ethoxy. The resulting oxygen-containing aluminoxanes are not in general pure compounds but mixtures of oligomers of the formula (A). The preferred aluminoxane is methylaluminoxane (MAO). Since the aluminoxanes used according to the invention as cocatalysts are not, owing to their mode of preparation, pure compounds, the molarity of aluminoxane solutions hereinafter is based on their aluminium content. Boron containing cocatalyst According to the present invention, the aluminoxane cocatalyst can be used in combination with a boron containing cocatalyst. It will be appreciated by the person skilled in the art that where boron based cocatalysts are employed, it is normal to pre-alkylate the complex by reaction thereof with an aluminium alkyl compound, such as TIBA. This procedure is well known and any suitable aluminium alkyl, e.g. Al(C1-C6 alkyl)3 can be used. Preferred aluminium alkyl compounds are triethylaluminium, tri- isobutylaluminium, tri-isohexylaluminium, tri-n-octylaluminium and tri-isooctylaluminium. Alternatively, when a borate cocatalyst is used, the metallocene complex is in its alkylated version, that is for example a dimethyl or dibenzyl metallocene complex can be used. Boron containing cocatalysts of interest include those of formula (B): BY3 (B) wherein Y is the same or different and is hydrogen, C1-C10-haloalkyl, or C6-C20-haloaryl, or fluorine, chlorine, bromine or iodine.

Preferred examples for Y are fluorine, trifluoromethyl, unsaturated groups such as haloaryl like p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5- trifluorophenyl and 3,5-di(trifluoromethyl)phenyl. Most preferably, Y are fluorine, trifluoromethyl, aromatic fluorinated groups such as p- fluorophenyl, 3,5-difluorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl and 3,5- di(trifluoromethyl)phenyl. Preferred boron containing cocatalysts of formula (B) are trifluoroborane, tris(4- fluorophenyl)borane, tris(3,5-difluorophenyl)borane, tris(2,4,6-trifluorophenyl)borane, tris(penta-fluorophenyl)borane, and/or tris(3,4,5-trifluorophenyl)borane. Particular preference is given to tris(pentafluorophenyl)borane. However it is preferred that borates are used, i.e. compounds containing a borate anion. These compounds have formula (C): Z4B^–-W⁺ (C) wherein Z is a substituted phenyl derivative, said substituent being halo-C1-C6-alkyl or halogen; and W⁺ is a cationic counterion. Preferably the substituents of Z are fluoro or trifluoromethyl. Most preferably, the phenyl group is perfluorinated. The borate anion Z4B^– is preferably a weakly-coordinating anion such as tetrakis(pentafluorophenyl)borate. Suitable cationic counterions W⁺ are triarylcarbenium such as triphenylcarbenium or protonated amine or aniline derivatives such as methylammonium, anilinium, dimethylammonium, diethylammonium, N- methylanilinium, diphenylammonium, N,N-dimethylanilinium, trimethylammonium, triethylammonium, tri-n-butylammonium, methyldiphenylammonium, pyridinium, p-bromo-N,N- dimethylanilinium or p-nitro-N,N- dimethylanilinium. Preferred ionic compounds which can be used according to the present invention include: tributylammoniumtetra(pentafluorophenyl)borate, tributylammoniumtetra(trifluoromethylphenyl)borate, tributylammoniumtetra(4-fluorophenyl)borate, N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N-di(propyl)ammoniumtetrakis(pentafluorophenyl)borate, di(cyclohexyl)ammoniumtetrakist(pentafluorophenyl)borate, triphenylcarbeniumtetrakis(pentafluorophenyl)borate, or ferroceniumtetrakis(pentafluorophenyl)borate. Preference is given to triphenylcarbeniumtetrakis(pentafluorophenyl) borate, N,N- dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate or N,N- dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate. Mostly preferred are triphenylcarbeniumtetrakis(pentafluorophenyl) borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N- dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, or N,N- dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate. Catalyst Manufacture The metallocene catalysts can be used in supported or unsupported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina or zirconia or a mixed oxide such as silica-alumina, in particular silica, alumina or silica-alumina. The use of a silica support is preferred. The skilled person is aware of the procedures required to support a metallocene catalyst. Especially preferably the support is a porous material so that the complex may be loaded into the pores of the support, e.g. using a process analogous to those described in WO94/14856, WO95/12622 and WO2006/097497. The particle size is not critical but is preferably in the range 5 to 200 μm, more preferably 20 to 80 μm. The use of these supports is routine in the art. Especially preferred procedures for producing such supported catalysts are those described in WO2020/239598, and WO2020/239603. In another embodiment, no external carrier is used but the catalyst is still presented in solid particulate form. Thus, no external support material, such as inert organic or inorganic carrier, for example silica as described above is employed. Such catalysts can be prepared as described for example in WO2003/051934, WO2014/060540, and WO2019/179959. The particulate support material used is an inorganic porous support such as a silica, alumina or a mixed oxide such as silica-alumina, in particular silica. The use of a silica support is preferred. The complex may be loaded into the pores of the particulate support, e.g. using a process analogous to those described in W094/14856, W095/12622, W02006/097497, and EP18282666. The average particle size of the support such as silica support can be typically from 10 to 100 µm. However, it has turned out that special advantages can be obtained, if the support has an average particle size from 15 to 80 µm, preferably from 18 to 50 µm. The average pore size of the inorganic porous support such as silica support can be in the range from 10 to 100 nm and the pore volume from 1 to 3 mL/g. The pore diameter of the inorganic porous support such as silica support can be in the range from 20 to 40 nm. The surface area of the inorganic porous support such as silica support can be typically in the range from 100 to 400 m²/g. Examples of suitable support materials are, for instance, ES757 produced and marketed by PQ Corporation, Sylopol 948 produced and marketed by Grace or SUNSPERA DM-L-303 silica produced by AGC Si-Tech Co. Supports can be optionally calcined prior to the use in catalyst preparation in order to reach optimal silanol group content. The use of these supports is routine in the art. The catalyst can contain from 5 to 500 µmol, such as 10 to 100 µmol of transition metal of the metallocene per gram of support such as silica, and 3 to 15 mmol of Al per gram of support such as silica. The present polymerization catalyst may be produced by e.g. as described in WO2020/239603 or WO2020/239598. A polymerization catalyst containing such metallocenes may be produced by a process including the steps of P1-a) combining the porous inorganic support with a first portion of the aluminoxane cocatalyst in a hydrocarbon solvent to obtain aluminoxane cocatalyst treated support, optionally followed by thermal treatment of the aluminoxane treated support; P1-b) dissolving the metallocene complex in a hydrocarbon solvent, preferably an aromatic solvent, more preferably toluene, optionally adding a second portion of the aluminoxane cocatalyst in the hydrocarbon solvent optionally the boron containing cocatalyst wherein the amount of the first portion of the aluminoxane cocatalyst added in step P1-a) is 75.0 to 100.0 wt% of the total amount of aluminoxane cocatalyst and the amount the second portion of the aluminoxane cocatalyst added in step P1-b) is 0.0 to 25.0 wt% of the total amount of aluminoxane cocatalyst and the boron containing cocatalyst, when present, is added in an amount that a boron/M molar ratio of feed amounts in the range of 0.1 :1 to 10:1 is reached; P1-c) adding the solution obtained in step P1-b) to the aluminoxane cocatalyst treated support obtained in step P1-a) and optionally P1-d) drying the so obtained supported catalyst system. In step P1-b) of the process, the components can be mixed in any order. The optional boron containing cocatalyst can be mixed with the metallocene complex dissolved in the hydrocarbon solvent and followed by addition the optional aluminoxane, or the metallocene complex dissolved in the hydrocarbon solvent can be mixed with the optional aluminoxane and a hydrocarbon followed by addition of boron containing cocatalyst and so on. In some embodiments, all components might be combined simultaneously. Only one impregnation step is used, i.e. the treated support of step P1-a) is loaded only in one step with the metallocene. In a preferred aspect of the present invention the process comprises P2-a) combining the porous inorganic support with aluminoxane cocatalyst in a hydrocarbon solvent to obtain aluminoxane cocatalyst treated support, optionally followed by thermal treatment of the aluminoxane treated support, filtering off the hydrocarbon solvent, optionally washing with an aromatic solvent, repeating the filtration and washing steps to remove unreacted aluminium compounds; drying the final aluminoxane cocatalyst treated support; P2-b) dissolving the metallocene in a hydrocarbon solvent optionally adding a methylaluminoxane cocatalyst in a hydrocarbon solvent, wherein the amount of methylaluminoxane cocatalyst added in step P2-a) is 75.0 to 100.0 wt% of the total amount of methylaluminoxane cocatalyst and the amount of aluminoxane cocatalyst added in step P2-b) is 0.0 to 25.0 wt% of the total amount of methylaluminoxane cocatalyst, to obtain a metallocene solution optionally comprising aluminoxane cocatalyst; P2-c) adding the metallocene solution to the aluminoxane cocatalyst treated support obtained in step P2-a) and optionally P2-d) drying the so obtained supported catalyst system. If desired, the obtained supported catalyst system may be provided as an oil slurry with a desired solid content. The solid catalyst content in the slurry may be e.g. up to 30 wt%, like up to 25 wt%. The amounts of support, aluminoxane, preferably MAO, boron containing cocatalyst and metallocene depend on the desired herein defined ratios (boron/M, Al/M, Al/SiO₂, M/SiO₂). Polymers It is a feature of the invention that the claimed process enables the formation of polypropylene with very high melting point. These features can be achieved at commercially interesting polymerization temperatures, e.g. 60 °C or more, such as from 60 °C to 90 °C. The polydispersity index (Mw/Mn) of the polymers depend on the polymerization conditions in each reactor, and can be between 2.0 and 7.0. In a particular embodiment, the propylene polymers obtained using the catalysts of the invention have a narrow polydispersity index (Mw/Mn), between 2.0 and 4.0. Propylene copolymers Propylene copolymers with ethylene or with C4-C10 alpha olefin comonomers, preferably propylene terpolymers with ethylene and with C4-C10 alpha olefin comonomers, more preferably propylene-ethylene-butene terpolymers, made by the process of the invention can be made with high productivity. The productivity of the polymerization process may be at least 13 kg of polymer per gram of catalyst, preferably at least 14 kg of polymer per gram of catalyst, more preferably at least 14.5 kg polymer per gram of catalyst. The polymerization temperature may be above 60°C, preferably above 65°C. The process of the invention may be used to produce propylene copolymers, preferably propylene terpolymers, having relatively low MFR2. For example, the MFR2 may below 15, preferably below 10 and, for example, below 8. When such copolymers are produced in liquid monomers, the MFR2 may be below 10, preferably below 8. The propylene copolymers may have a total comonomer content of 0.5 to 10 weight %, preferably 1.0 to 8.0 weight %, for example, 2 to 7 weight %. For example, the propylene copolymer may be a terpolymer having an ethylene content of 0.5 to 2 weight %, and a C₄-C₁₀ alpha olefin comonomer content of 4.0 to 8.0 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 0.5 to 3.0 weight %, preferably 0.8 to 1.8 weight %. The propylene copolymer may be a terpolymer having a C₄-C₁₀ alpha olefin comonomer content of 2.0 to 10 weight %, preferably 4.5 to 7.0 weight %, such as 5.0 to 6.0 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 0.9 to 1.5 weight %, and a C₄-C₁₀ alpha olefin comonomer content of 4.8 to 6.5 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 1.0 to 1.3 weight %, and a C₄- C₁₀ alpha olefin comonomer content of 5.0 to 6.0 weight %. In one embodiment, the propylene copolymer may be a terpolymer having an ethylene content of 0.8 to 1.8 weight %, and a C4 alpha olefin comonomer content of 4.5 to 7 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 0.9 to 1.5 weight %, and a C₄ alpha olefin comonomer content of 4.8 to 6.5 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 1.0 to 1.3 weight %, and a C4 alpha olefin comonomer content of 5.0 to 6.0 weight %. In some examples, the propylene copolymer is a terpolymer having an ethylene content and C4-C10 alpha olefin comonomer (e.g. C4 alpha olefin comonomer) content as described above in combination with an MFR2 may below 15, preferably below 10 and, for example, below 8. An advantage of certain embodiments of the present disclosure is that propylene copolymers having such MFR2 properties may be produced at desirable levels of productivity. Preferably, such propylene copolymers may be produced at relatively high levels of productivity, for example, of at least 13 kg of polymer per gram of catalyst, preferably at least 14 kg of polymer per gram of catalyst, more preferably at least 14.5 kg polymer per gram of catalyst. Preferably, the propylene copolymer has an MFR2 of 0.5 to 20 g/10min, more preferably 1.0 to 10 g/10min, especially 2.0 to 8.0 g/10min. The polymers made by the catalysts of the description are useful in all kinds of end articles such as pipes, films (cast, blown or BOPP films, such as for example BOPP for capacitor film), fibers (such as spun-bond and melt-blown fibers), moulded articles (e.g. injection moulded, blow moulded, rotomoulded articles), extrusion coatings and so on. EXAMPLES The invention will now be illustrated by reference to the following non-limiting Examples. Synthesis of MC-CE1 Synthesis of this metallocene was carried out as described in WO2019/179959, MC-2. Synthesis of MC-IE1 Synthesis of this metallocene was carried out as described in WO2018/091684, MC-IE1. Synthesis of MC-IE2 Ethylmalonic acid A solution of 196.4 g (3.5 mol) of potassium hydroxide in 1000 cm³ of water was added to a solution of 188.2 g (1.0 mol) of diethyl ethylmalonate in 500 ml of methanol. The resulting mixture was refluxed for 5 h, then ethanol and methanol were distilled off. Then, 1000 cm³ of water was added and the obtained mixture was acidified with 12 M HCl to pH 1.0. Ethylmalonic acid was extracted with 5^300 ml of ether. The combined extract was evaporated to dryness and the residue was dried under vacuum. This procedure gave 120.2 g (91.0%) of ethylmalonic acid as white solid. ¹H NMR (DMSO-d6): δ 4.28 (br.s, 2H), 3.12 (d, J = 7.4 Hz, 1H), 1.71 (quin, J = 7.40 Hz, 2H), 0.86 (t, J = 7.4 Hz, 3H).¹³C NMR (CDCl3): δ 171.12, 53.36, 22.01, 11.95. 2-Ethylacrylic acid Diethylamine (108.2 ml, 76.82 g, 1.05 mol) was added dropwise at 5 °C to a solution of ethylmalonic acid (118.8 g, 899.2 mmol) in 1300 ml of ethyl acetate. Paraform (38.4 g, 1.28 mol) was added to the obtained suspension. The resulting mixture was refluxed for 5 h, then cooled to 5 °C, then 600 ml of ether and 1700 cm³ of 2 M HCl were added. After mixing, the organic layer was separated, the aqueous layer was additionally extracted with 2^700 ml of ether. The combined organic extract was dried over Na₂SO₄ and then carefully evaporated to dryness. The residue was purified by vacuum distillation to give 2-ethylacrylic acid, bp 75- 77^oC/6 mm Hg. Yield 79.8 g (88.6%) of a colorless liquid. ¹H NMR (CDCl₃): δ 12.55 (br.s, 1H), 6.28 (m, 1H), 5.64 (m, 1H), 2.32 (qm, J = 7.5 Hz, 2H), 1.08 (t, J = 7.5 Hz, 3H). 6-tert-Butyl-5-methoxy-2-ethylindan-1-one -ethylacrylic acid (47.6 g, 475.5 mmol, 1.27 equiv.) was added to Eaton's reagent obtained from 103.5 g of P₄O₁₀ and 520 ml of MeSO₃H at 50 °C. To this rapidly stirred mixture, 1-tert- butyl-2-methoxybenzene (61.7 g, 375.7 mmol) was added dropwise over ca.1 h at 50-53 °C (hot water bath). The resulting mixture was stirred for 1 h at this temperature, then cooled to room temperature, and poured on a mixture of 1.0 liter of cold water and 1 kg of ice. The crude product was extracted with 3^400 ml of dichloromethane. The combined organic extract was washed with aqueous K₂CO₃, dried over K₂CO₃, filtered through a short pad of silica gel 60 (40-63 µm) and then evaporated to dryness. The residue was purified by vacuum distillation to give 81.18 g (87.7 %, ca. 90% purity) of 6-tert-butyl-5-methoxy-2-ethylindan-1-one as a yellowish oil (bp 150-170^oC/5 mm Hg). ¹H NMR (CDCl₃): δ 7.65 (s, 1H), 6.85 (s, 1H), 3.90 (s, 3H), 3.20 (dd, J = 17.2 Hz, J = 7.7 Hz, 1H), 2.71 (dd, J = 17.2 Hz, J = 3.6 Hz, 1H), 2.59-2.51 (m, 1H), 1.99-1.87 (m, 1H), 1.54-1.41 (m, 1H), 1.35 (s, 9H), 0.97 (t, J = 7.4 Hz, 3H).¹³C NMR (CDCl₃): δ 207.59, 164.52, 154.75, 138.65, 129.31, 121.87, 107.72, 55.15, 48.86, 35.00, 31.93, 29.54, 24.61, 11.56. 4-Bromo-6-tert-butyl-2-ethyl-5-methoxyindan-1-one Bromine (18.5 ml, 57.4 g, 359.1 mmol) was added dropwise over 5 min at 5 °C to a mixture of 6-tert-butyl-2-ethyl-5-methoxyindan-1-one (81.18 g, 329.5 mmol), 100.4 g of sodium acetate, 3.0 g of ⁿBu4NI, 280 ml of dichloromethane, and 570 ml of water. This mixture was stirred for 2 h at 5 °C, then a solution of 46.3 g of sodium acetate in 260 ml of water was added followed by addition of 9.7 ml (30.1 g, 188.3 mmol) of bromine. The resulting mixture was additionally stirred for 1 h at this temperature and then washed by aqueous Na2SO3 to remove excess bromine. The crude product was extracted with 3^250 ml of dichloromethane. The combined organic extract was dried over K₂CO₃, evaporated to dryness, and the residue was dried under vacuum. This procedure gave 105.3 g (98.1%, ca.90% purity) of 4-bromo-6-tert-butyl-2-ethyl- 5-methoxyindan-1-one as a yellowish oil which was used without further purification. ¹H NMR (CDCl₃): δ 7.69 (s, 1H), 4.03 (s, 3H), 3.21 (dd, J = 17.6 Hz, J = 7.8 Hz, 1H), 2.70 (dd, J = 17.6 Hz, J = 3.7 Hz, 1H), 2.66-2.58 (m, 1H), 2.03-1.91 (m, 1H), 1.60-1.47 (m, 1H), 1.40 (s, 9H), 1.03 (t, J = 7.4 Hz, 3H). ¹³C NMR (CDCl₃): δ 207.14, 162.57, 154.07, 145.20, 133.07, 121.13, 116.50, 61.45, 48.79, 35.46, 33.36, 30.45, 24.34, 11.43. 6-tert-Butyl-2-ethyl-5-methoxy-4-(3,5-dimethylphenyl)-indan-1-one A mixture of 64.08 g (197.0 mmol) of 4-bromo-6-tert-butyl-2-ethyl-5-methoxyindan-1-one, 37.32 g (248.8 mmol, 1.26 equiv.) of 3,5-dimethylphenylboronic acid, 1.02 g (2.0 mmol, 1 mol.%) of Pd(P^tBu3)2, 63.4 g of Na2CO3, 325 ml of 2-methyltetrahydrofurane, and 290 ml of water was refluxed for 6 h. Then 500 ml of water was added, the organic layer was separated, and the aqueous layer was extracted with 200 ml of dichloromethane. The combined organic extract was dried over K2CO3 and then evaporated to dryness to give slightly yellowish oil. The product was isolated by flash-chromatography on silica gel 60 (40-63 µm, eluent: hexanes-dichloromethane = 1:1 and then 1:5, vol.). Yield 62.95 g (91.2%, purity ca.95%) of a slightly yellowish oil. ¹H NMR (CDCl₃): δ 7.73 (s, 1H), 7.03 (s, 1H), 7.02 (s, 2H), 3.32 (s, 3H), 3.06 (dd, J = 18.3 Hz, J = 8.6 Hz, 1H), 2.57-2.47 (m, 2H), 2.39 (s, 6H), 2.00-1.87 (m, 1H), 1.54-1.40 (m, 1H), 1.42 (s, 9H), 0.95 (t, J = 7.4 Hz, 3H).¹³C NMR (CDCl₃): δ 208.30, 163.42, 153.15, 143.21, 138.06, 136.27, 132.68, 131.42, 129.07, 127.17, 121.11, 60.47, 49.00, 35.33, 31.69, 30.49, 24.48, 21.36, 11.67. 5-tert-Butyl-2-ethyl-6-methoxy-7-(3,5-dimethylphenyl)-1H-indene NaBH₄ (10.2 g, 269.6 mmol, 1.5 equiv.) was added to a solution of 62.95 g (179.6 mmol) of 6- tert-butyl-2-ethyl-5-methoxy-4-(3,5-dimethylphenyl)-indan-1-one in 300 ml of THF cooled to 5 °C. To this mixture 150 ml of MeOH was added dropwise over ca.5 h at 5 °C, and the resulting mixture was stirred overnight at room temperature. Then, this mixture was evaporated to dryness, 700 ml of dichloromethane and 700 ml water were added to the residue, and the so obtained mixture was acidified with 2 M HCl to pH~6.5. The organic layer was separated, the aqueous layer was additionally extracted with 100 ml of dichloromethane. The combined organic extract was passed through a pad (~30 ml) of silica gel 60 (40-63 µm; eluent: dichloromethane) to get rid of most of the palladium black. The obtained elute was evaporated to dryness to give a grey oil. This oil was dissolved in 300 ml of toluene and TsOH (0.3 g) was added to it. This mixture was refluxed with Dean-Stark head for 10 min and then cooled to room temperature using a water bath. The formed solution was washed with 10% Na2CO3, the organic layer was separated, the aqueous layer was extracted with 150 ml of dichloromethane. The combined organic extract was dried over K2CO3 and then evaporated to dryness. The crude product was purified by flash chromatography on silica gel 60 (40-63 µm, hexanes-dichloromethane = 10:1) followed by vacuum distillation to give 53.14 g (88.5%) of 5-tert-butyl-2-ethyl-6-methoxy-7-(3,5-dimethylphenyl)-1H-indene as a yellowish oil (bp 175- 195^oC/2 mm Hg). ¹H NMR (CDCl3): δ 7.22 (s, 1H), 7.09 (s, 2H), 6.99 (s, 1H), 6.45 (t, J = 1.4 Hz, 1H), 3.25 (s, 3H), 3.13 (s, 2H), 2.41 (q, J = 7.4 Hz, 2H), 2.37 (s, 6H), 1.44 (s, 9H), 1.14 (d, J = 7.4 Hz, 3H). ¹³C NMR (CDCl3): δ 154.25, 151.76, 141.51, 140.88, 140.43, 138.31, 137.66, 131.91, 128.46, 127.20, 124.97, 117.17, 60.66, 41.00, 35.13, 31.01, 24.25, 21.43, 13.47. Bis[6-tert-butyl-4-(3,5-dimethylphenyl)-5-methoxy-2-ethyl-1H-inden-1-yl]dimethylsilane ⁿBuLi in hexanes (2.5 M, 16.7 ml, 41.75 mmol) was added in one portion to a solution of 5- tert-butyl-7-(3,5-dimethylphenyl)-2-ethyl-6-methoxy-1H-indene (13.96 g, 41.74 mmol) in 250 ml of ether at –50 °C. This mixture was stirred overnight at room temperature, then the resulting yellow-orange solution was cooled to –50 °C, and 200 mg of CuCN was added. The obtained mixture was stirred for 15 min at –25 °C (a large amount of yellow precipitate formed), and then 2.69 g (20.84 mmol) of dichlorodimethylsilane was added in one portion. This mixture was stirred for 5 h at room temperature, then filtered through a pad of silica gel 60 (40-63 µm) which was additionally washed with 20 ml of n-hexane. The combined elute was evaporated to dryness, and the residue was dried under vacuum at elevated temperature to give 15.17 g (ca. 100% of ca. 85% purity) of a ca. 30:70 mixture of the rac- and meso-pro-ligands as a slightly yellowish glassy solid which was used without further purification. ¹H NMR (CDCl3): δ 7.56 and 7.32 (2s, sum 2H), 7.12 (s, 4H), 6.99 (s, 2H), 6.46 and 6.44 (2s, sum 2H), 3.79 and 3.59 (2s, sum 2H), 3.26 (2s, sum 6H), 2.57-2.25 (m, 16H), 1.45 and 1.44 (2s, sum 18H), 1.13 and 1.09 (2t, J = 7.4 Hz, sum 6H), -0.10, -0.18 and -0.25 (3s, sum 6H). ¹³C NMR (CDCl3): δ 155.32, 154.45, 153.98, 143.49, 143.40, 139.23, 139.16, 138.16, 137.52, 137.50, 137.16, 137.07, 128.24, 127.94, 127.68, 127.65, 123.72, 123.50, 120.58, 120.32, 60.48, 45.73, 45.70, 35.15, 35.13, 31.29, 31.20, 24.88, 24.82, 21.45, 13.85, 13.81, -4.08, - 4.24, -5.60. Rac-dimethylsilanediyl-bis[2-ethyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butyl- inden-1-yl]zirconium dichloride ⁿBuLi in hexanes (2.5 M, 16.2 ml, 40.5 mmol) was added in one portion to a yellowish solution of bis[6-tert-butyl-4-(3,5-dimethylphenyl)-5-methoxy-2-ethyl-1H-inden-1-yl]dimethylsilane (14.62 g, ca.20.16 mmol) in 100 ml of ⁿBu2O at room temperature. This mixture was stirred for 15 h at room temperature, then the resulting yellow suspension was cooled to 0 °C in an ice-bath, and ZrCl4 (4.7 g, 20.17 mmol) was added. The reaction mixture was stirred for 24 h at room temperature to give a red suspension. This mixture was evaporated to dryness (to the state of orange-red foam). This solid was extracted with 200 ml of hot n-hexane, the so obtained suspension was filtered through glass frit (G4) to remove LiCl, and the resulting filtrate was evaporated to ca.125 ml. The orange solid precipitated from this solution overnight at room temperature was collected and dried under vacuum. This procedure gave 9.3 g of a ca.1:1 mixture of rac- and meso- isomers containing 0.5 mol of n-hexane per mol of Zr. The mother liquor was evaporated to the state of oil, the residue was dissolved in 20 ml of n- pentane, and the resulting solution was stirred overnight at room temperature. The orange solid precipitated from this solution was collected and dried under vacuum. This procedure gave 2.9 g of a ca.1:1 mixture of rac- and meso- isomers containing 0.5 mol of n-pentane per mol of Zr. LiCl (662 mg, 15.6 mmol, 2.0 equiv.) and 12 ml of THF were added to 7.2 g (7.76 mmol) of a ca.1:1 mixture of rac- and meso- isomers, and the obtained mixture was stirred for 4 days at 90 °C. On the evidence of NMR spectroscopy, the resulting mixture contained a ca.76:24 mixture of rac- and meso- isomers. Then, THF was evaporated under vacuum, 30 ml of toluene was added to the residue. The resulting mixture was evaporated under vacuum to remove residual THF. To this residue, 100 ml of toluene was added, the mixture was heated to ca.90 °C and then filtered through glass filter (G4) to remove insoluble inorganic salts. The filtrate was evaporated to 40 ml and again filtered through glass frit (G4). The so obtained filtrate was evaporated to ca.15 ml, heated to ca.60 °C, and 5 ml of n-hexane was added. After stirring for 5 min, the precipitated yellow solid was filtered off (G4), washed with 8 ml of toluene/n-hexane (1:5, vol.), and dried under vacuum. This procedure gave 1.08 g of the pure rac-isomer. Rac-isomer: ¹H NMR (CDCl3): δ 7.48 (s, 2H), 7.45-7.00 (very br.s, 4H), 6.97 (s, 2H), 6.61 (s, 2H), 3.43 (s, 6H), 2.75-2.63 (m, 2H), 2.40-2.27 (m, 2H), 2.36 (s, 12H), 1.38 (s, 18H), 1.27 (s, 6H), 1.04 (t, J = 7.5 Hz, 6H). ¹³C NMR (CDCl3): δ 159.74, 144.10, 142.06, 137.84 (br.s), 136.83, 133.67, 128.81, 127.44, 127.18, 123.05, 120.94, 119.00, 80.51, 62.68, 35.73, 30.38, 25.97, 21.50, 16.85, 2.74. Synthesis of indenes for MC-IE3 and MC-IE4 The common intermediate 2,3-dihydrobenzodioxine (CAS# 493-09-4, purity 97%) was purchased from ABCR. 7-Methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one Methacryloyl chloride (94.39 g, 903.0 mmol) was added dropwise over 15 min to a suspension of AlCl₃ (126.4 g, 947.7 mmol) in 750 ml of dichloromethane cooled to –78 °C a, followed by dropwise addition of benzo-1,4-dioxane (123.0 g, 903.4 mmol). The reaction mixture was heated to room temperature in 1 hour, then the reaction mixture was stirred for 19 h at room temperature. The resulting mixture was poured onto 2000 cm³ of crushed ice. The organic layer was separated, the aqueous layer was extracted with 300 ml of dichloromethane. The combined organic extract was washed with aqueous K₂CO₃, dried over K₂CO₃, and passed through a short pad of silica gel 60 (40-63 µm) which was additionally washed with 200 ml of dichloromethane. The combined organic elute was evaporated to dryness to give 167.5 g (90.8%, purity ca.90%) of 7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one as a white solid mass which was used without further purification. 9-Bromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one A mixture of 93.3 g (456.9 mmol) of 7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin- 6-one, 139.0 g of NaOAc, 3.5 g of ⁿBu4NBr, 400 ml of dichloromethane, and 800 ml of water was cooled to +5 °C, then bromine (23.5 ml, 73.3 g, 458.7 mmol) was added dropwise over 20 min at this temperature. The resulting mixture was stirred for 1 h at this temperature, then a solution of 63.6 g of NaOAc in 400 ml of water was added followed by 11.0 ml (34.3 g, 214.7 mmol) of bromine for 10 min. This mixture was stirred additionally for 1 h at 5 °C, then washed by aqueous Na₂SO₃ to neutralize any excess bromine. The organic layer was separated, and the aqueous phase was additionally extracted with 2´200 ml of dichloromethane. The combined organic extract was filtered through a pad of silica gel 60 (40-63 µm) which was additionally washed with 200 ml of dichloromethane. The combined organic elute was evaporated to ca.200 ml, and 200 ml of n-hexane was added. The precipitated white solid was filtered off (G3) and dried under vacuum to give 56.56 g (43.7%) of pure 9-bromo-7- methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one. The mother liquor was evaporated to give a semi-solid residue. This residue was triturated with 65 ml of dichloromethane, then 65 ml of n-hexane was added. The precipitated white solid was filtered off (G3) and dried under vacuum to give 34.54 g of a 2:1 mixture of 9-bromo-7-methyl-2,3,7,8- tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one and 5,9-dibromo-7-methyl-2,3,7,8-tetrahydro- 6H-indeno[5,6-b][1,4]dioxin-6-one, respectively. ¹H NMR (CDCl₃): δ 7.22 (s, 1H), 4.47-4.42 (m, 2H), 4.32-4.27 (m, 2H), 3.26 (dd, J = 17.3 Hz, J = 7.8 Hz, 1H), 2.70 (dqd, J = 7.8 Hz, J = 7.5 Hz, J = 3.8 Hz, 1H), 2.57 (dd, J = 17.3 Hz, J = 3.8 Hz, 1H), 1.30 (d, J = 7.5 Hz, 3H).¹³C NMR (CDCl₃): δ 207.52, 147.15, 146.65, 144.14, 130.05, 110.79, 108.95, 65.28, 63.60, 41.92, 35.34, 16.36. 9-(3,5-Dimethylphenyl)-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one A mixture of 55.48 g (199.49 mmol) of 9-bromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6- b][1,4]dioxin-6-one, 37.84 g (252.3 mmol, 1.27 equiv.) of 3,5-dimethylphenyl-boronic acid, 1.04 g (2.04 mmol, 1 mol.%) of Pd(P^tBu3)2, 64.3 g of Na2CO3, 330 ml of 2- methyltetrahydrofurane, and 295 ml of water was refluxed for 2 h. Then 400 ml of water was added, the organic layer was separated, and the aqueous layer was extracted with 400 ml of dichloromethane. The combined organic extract was dried over K₂CO₃ and then evaporated to dryness to give a light brown solid mass. The product was isolated by flash-chromatography on silica gel 60 (40-63 µm, eluent: dichloromethane, then dichloromethane:ether = 1:10, vol.). The product containing fractions were combined and evaporated to dryness. The resulting solid mass was triturated with 200 ml of n-hexane. The formed precipitate was filtered off (G3), washed with 2´40 ml of n-hexane, and dried under vacuum. This procedure gave 59.5 g (96.7%) of 9-(3,5-dimethylphenyl)-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6- one as a white powder. ¹H NMR (CDCl₃): δ 7.27 (s, 1H), 7.03 (br.s, 1H), 6.95 (br.s, 2H), 4.30-4.23 (m, 4H), 3.10 (dd, J = 17.1 Hz, J = 7.8 Hz, 1H), 2.61 (dqd, J = 7.8 Hz, J = 7.6 Hz, J = 3.9 Hz, 1H), 2.42 (dd, J = 17.1 Hz, J = 3.9 Hz, 1H), 2.38 (s, 6H), 1.24 (d, J = 7.6 Hz, 3H).¹³C NMR (CDCl₃): δ 208.42, 146.77, 146.02, 143.90, 137.76, 134.19, 129.42, 129.21, 128.28, 127.15, 110.67, 64.72, 63.59, 41.97, 33.93, 21.35, 16.37. 5-(3,5-Dimethylphenyl)-7-methyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxine NaBH4 (11.0 g, 290.8 mmol, 1.5 equiv.) was added to a solution of 9-(3,5-dimethylphenyl)-7- methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (59.5 g, 193.0 mmol) in 550 ml of THF cooled to 5 °C. To this mixture, 200 ml of MeOH was added dropwise over ca.5 h at 5 °C, and the resulting mixture was stirred overnight at room temperature. Then, this mixture was evaporated to dryness, 1000 ml of dichloromethane and 1000 ml water were added to the residue, and the so obtained mixture was acidified with 2 M HCl to pH~6.5. The organic layer was separated, the aqueous layer was additionally extracted with 50 ml of dichloromethane. The combined organic extract was passed through a pad (~30 ml) of silica gel 60 (40-63 µm; eluent: dichloromethane) to get rid of most of the palladium black. The obtained elute was evaporated to dryness to give a white solid mass which was dissolved in 800 ml of toluene, preheated to ca.60 °C, then TsOH (1.0 g) was added. This mixture was refluxed with Dean-Stark head for 10 min. Then, the reaction mixture was quickly cooled to room temperature using an ice-water bath. The formed solution was washed with 10% aqueous K2CO3, the organic layer was separated, the aqueous layer was extracted with 100 ml of dichloromethane. The combined organic extract was dried over K2CO3, passed through a pad of silica gel 6040-63 µm), and the so obtained elute was evaporated to dryness. The crude product was triturated with 200 ml of n-hexane. The formed precipitate was filtered off (G3), then washed with 2x20 ml of n-hexane, and dried under vacuum. This procedure gave 53.08 g (96.7%) of 5-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxine as a white powder. ¹H NMR (CDCl₃): δ 7.01 (br.s, 2H), 6.98 (br.s, 1H), 6.76 (s, 1H), 6.37 (m, 1H), 4.24-4.21 (m, 2H), 4.21-4.17 (m, 2H), 3.08 (s, 2H), 2.36 (s, 6H), 2.05 (m, 3H).¹³C NMR (CDCl₃): δ 145.32, 142.45, 138.59, 137.46, 136.35, 135.27, 128.94, 127.26, 127.18, 126.28, 107.50, 64.40, 64.15, 42.18, 21.41, 16.66. 5,9-Dibromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (method A) A solution of 7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (37.0 g, 181.2 mmol, as prepared above) in 50 ml of dichloromethane was added dropwise over 15 min to a suspension of AlCl3 (60.0 g, 500 mmol, 2.48 eq.) in 500 ml of dichloromethane at –50 °C. The reaction mixture was stirred for 5 min at this temperature, then bromine (19.0 ml, 59.26 g, 370.82 mmol, 2.05 eq.) was added dropwise over 15 min. The resulting mixture was stirred for 4 h at room temperature and then poured onto 2000 cm³ of crushed ice. The organic layer was separated, the aqueous layer was extracted with 300 ml of dichloromethane. The combined organic extract was washed with aqueous K2CO3, dried over K2CO3 and passed through a short pad of silica gel 60 (40-63 µm) which was additionally washed with 200 ml of dichloromethane. The combined organic elute was evaporated to ca.200 ml, and 200 ml of n- hexane was added. The precipitated white solid was filtered off (G3) and dried under vacuum to give 43.75 g (66.7%) of pure 5,9-dibromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6- b][1,4]dioxin-6-one. ¹H NMR (CDCl₃): δ 4.49-4.45 (m, 2H), 4.44-4.39 (m, 2H), 3.23 (dd, J = 17.4 Hz, J = 8.1 Hz, 1H), 2.73 (dqd, J = 8.1 Hz, J = 7.4 Hz, J = 4.1 Hz, 1H), 2.54 (dd, J = 17.4 Hz, J = 4.1 Hz, 1H), 1.32 (d, J = 7.4 Hz, 3H).¹³C NMR (CDCl₃): δ 205.34, 148.32, 146.49, 141.37, 127.55, 108.36, 107.25, 65.18, 64.30, 42.64, 34.70, 16.45. 5,9-Dibromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (method B) A mixture of 36.9 g (180.7 mmol) of 7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin- 6-one, 110.0 g of NaOAc, 1.5 g of ⁿBu4NBr, 300 ml of dichloromethane, and 600 ml of water was cooled to +5 °C, and then bromine (18.5 ml, 57.7 g, 361.1 mmol, 2.0 equiv.) was added dropwise over 20 min at this temperature. The resulting mixture was stirred for 1 h at this temperature, then 55.0 g of NaOAc was added followed by bromine (9.0 ml, 28.1 g, 175.7 mmol) added dropwise over 10 min. This mixture was stirred overnight at room temperature to give a light orange suspension with a large amount of precipitate. Aqueous Na2SO3 solution was added in order to neutralize excess bromine, followed by 500 ml of dichloromethane to dissolve the formed precipitate. The organic layer was separated, and the aqueous phase was extracted with 2x300 ml of dichloromethane. The combined organic extract was filtered through a pad of silica gel 60 (40-63 µm) which was additionally washed with 200 ml of dichloromethane. The combined organic elute was evaporated to ca.200 ml. The precipitated pink solid was filtered off (G3) and dried under vacuum to give 32.58 g (49.8%) of pure 5,9- dibromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one. 50 ml of n-hexane was added to the mother liquor, and the resulting mixture was evaporated to ca.50 ml. The precipitated white solid was filtered off (G3), washed with 2x10 ml of n-hexane, and dried under vacuum to give 13.69 g of a 93:7 mixture of 5,9-dibromo-7-methyl-2,3,7,8-tetrahydro- 6H-indeno[5,6-b][1,4]dioxin-6-one and 9-bromo-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6- b][1,4]dioxin-6-one, respectively. 5,9-Bis(3,5-dimethylphenyl)-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4] dioxin-6-one A mixture of 58.82 g (162.48 mmol) of 5,9-dibromo-7-methyl-2,3,7,8-tetrahydro-6H- indeno[5,6-b][1,4]dioxin-6-one, 54.83 g (365.6 mmol, 2.25 equiv.) of 3,5- dimethylphenylboronic acid, 1.3 g (2.54 mmol, 1.57 mol.%) of Pd(P^tBu3)2, 93.1 g of Na2CO3, 600 ml of 2-methyltetrahydrofurane, and 420 ml of water was refluxed for 5 h. Then, 500 ml of water was added, the organic layer was separated, and the aqueous layer was extracted with 400 ml of dichloromethane. The combined organic extract was dried over K2CO3 and then evaporated to dryness to give a brownish yellow solid mass. The product was isolated by flash-chromatography on silica gel 60 (40-63 µm, eluent: dichloromethane). This procedure gave 66.4 g (99.1%) of 5,9-bis(3,5-dimethylphenyl)-7-methyl-2,3,7,8-tetrahydro-6H- indeno[5,6-b][1,4]-dioxin-6-one as a yellow solid mass. ¹H NMR (CDCl3): δ 7.04 (s, 1H), 7.01 (s, 1H), 6.99 (s, 2H), 6.97 (s, 2H), 4.26-4.20 (m, 2H), 4.20-4.14 (m, 2H), 3.07 (dd, J = 17.1 Hz, J = 8.0 Hz, 1H), 2.55 (dqd, J = 8.0 Hz, J = 7.3 Hz, J = 4.5 Hz, 1H), 2.40 (dd, J = 17.1 Hz, J = 4.5 Hz, 1H), 2.39 (s, 6H), 2.36 (s, 6H), 1.16 (d, J = 7.3 Hz, 3H). ¹³C NMR (CDCl3): δ 207.03, 146.02, 145.93, 140.67, 137.73, 136.68, 134.42, 132.71, 129.47, 129.33, 128.48, 127.57, 127.26, 127.14, 126.18, 64.47, 63.65, 42.40, 33.37, 21.42, 21.35, 16.06. 5,9-Bis(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxine NaBH4 (9.2 g, 243.2 mmol, 1.51 equiv.) was added to a solution of 5,9-bis(3,5- dimethylphenyl)-7-methyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (66.4 g, 161.0 mmol) in 550 ml of THF cooled to 5 °C. To this mixture, 200 ml of MeOH was added dropwise over ca. 5 h at 5 °C, and the resulting mixture was stirred overnight at room temperature. Then, this mixture was evaporated to dryness, 1000 ml of dichloromethane and 1000 ml water were added to the residue, and the so obtained mixture was acidified with 2 M HCl to pH~6.5. The organic layer was separated, the aqueous layer was additionally extracted with 50 ml of dichloromethane. The combined organic extract was passed through a pad (~30 ml) of silica gel 60 (40-63 µm; eluent: dichloromethane) to get rid of most of the palladium black. The obtained elute was evaporated to dryness to give a white solid mass, which was then dissolved in 700 ml of toluene, preheated to ca.60 °C, then 0.9 g of TsOH was added. This mixture was refluxed with Dean-Stark head for 10 min. Then, the reaction mixture was quickly cooled to room temperature using an ice-water bath. A significant amount of white precipitate formed during cooling of the obtained mixture to room temperature. The formed suspension was washed with 10% aqueous K₂CO₃, and dichloromethane was added to the resulting suspension until the precipitate was completely dissolved (total volume of the organic phase was ca.1200 ml). The organic layer was separated, the aqueous layer was extracted with 150 ml of dichloromethane. The combined organic extract was dried over K₂CO₃, passed through a pad of silica gel 60 (40-63 µm), and the so obtained elute was evaporated to dryness. The crude product was triturated with 200 ml of n-hexane, the formed precipitate was filtered off (G3), washed with 2x50 ml of n-hexane, and dried under vacuum. This procedure gave 61.57 g (96.5%) of 5,9-bis(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxine as a white powder. ¹H NMR (CDCl3): δ 7.08 (s, 2H), 7.06 (s, 2H), 7.00 (s, 2H), 6.29 (m, 1H), 4.23-4.17 (m, 4H), 3.15 (s, 2H), 2.38 (2s, sum 12H), 2.01 (m, 3H).¹³C NMR (CDCl3): δ 144.89, 139.42, 137.70, 137.49, 137.45, 137.31, 136.46, 135.96, 134.69, 128.94, 128.75, 128.10, 127.38, 126.35, 125.83, 122.10, 64.20, 42.52, 21.45, 16.72. 7-Ethyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one 2-ethylacryloyl chloride (27.6 g, 233 mmol) was added dropwise over 15 min to a suspension of AlCl3 (33.0 g, 244 mmol) in 300 ml of dichloromethane cooled to –78 °C, followed by dropwise addition of benzo-1,4-dioxane (31.7 g, 233 mmol). The temperature of the reaction mixture was raised to room temperature in 1 h, then the reaction mixture was stirred for 19 h at room temperature. The resulting mixture was poured onto 500 cm³ of crushed ice. The organic layer was separated, the aqueous layer was extracted with 2x100 ml of dichloromethane. The combined organic extract was washed with aqueous K₂CO₃, dried over K2CO3, and passed through a short pad of silica gel 60 (40-63 µm), which was additionally washed with 100 ml of dichloromethane. The combined organic elute was evaporated to dryness. The residue was washed with a mixture of 50 ml of n-hexane and ca. 4 ml of dichloromethane and then dried under vacuum to give 31.5 g (62%) of the title material as a white solid mass. ¹H NMR (CDCl₃): δ 7.23 (s, 1H), 6.89 (s, 1H), 4.33-4.31 (m, 2H), 4.27-4.25 (m, 2H), 3.18 (dd, J = 16.9 Hz, J = 7.7 Hz, 1H), 2.69 (dd, J = 16.9 Hz, J = 3.7 Hz, 1H), 2.57 (m, 1H), 1.99-1.89 (m, 1H), 1.55-1.44 (m, 1H), 0.98 (t, J = 7.4 Hz, 3H). ¹³C NMR (CDCl₃): δ 207.50, 149.88, 147.73, 143.53, 130.44, 113.94, 111.54, 64.58, 63.80, 48.98, 31.56, 24.56, 11.49. 9-Bromo-7-ethyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one A mixture of 15.7 g (72 mmol) of 7-ethyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one, 23.6 g of NaOAc, 0.6 g of ⁿBu₄NBr, 75 ml of dichloromethane, and 150 ml of water was cooled to +5 °C, then 3.71 ml (72 mmol) of bromine was added dropwise over 20 min at this temperature. The resulting mixture was stirred for 1 h at this temperature, then a solution of 4.9 g of NaOAc in 50 ml of water was added, and finally 0.8 ml (15 mmol) of bromine were added dropwise over 10 min. This mixture was stirred for 1 h at 5 °C, then the resulting mixture was washed with aqueous Na₂SO₃ to remove excess bromine. The organic layer was separated, and the aqueous layer was additionally extracted with 2x100 ml of dichloromethane. The combined organic extract was filtered through a pad of silica gel 60 (40- 63 µm) that was additionally washed with 50 ml of dichloromethane. The combined organic elute was evaporated to dryness. The residue was washed twice with 150 ml of n-hexane and dried under vacuum to give 17.8 g (83%, ca.93% purity) of the title material as a white solid mass.¹H NMR (CDCl₃): δ 7.22 (s, 1H), 4.46-4.44 (m, 2H), 4.30-4.28 (m, 2H), 3.18 (dd, J = 17.1 Hz, J = 7.6 Hz, 1H), 2.68-2.58 (m, 2H), 1.95 (m, 1H), 1.58-1.47 (m, 1H), 1.01 (t, J = 7.4 Hz, 3H).¹³C NMR (CDCl3): δ 207.09, 147.59, 146.69, 144.20, 130.77, 110.75, 109.07, 65.35, 63.67, 48.78, 32.86, 24.55, 11.49. 9-(3,5-Dimethylphenyl)-7-ethyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one A mixture of 17.28 g (58 mmol) of 9-bromo-7-ethyl-2,3,7,8-tetrahydro-6H-indeno[5,6- b][1,4]dioxin-6-one, 11.05 g (73.6 mmol, 1.27 equiv.) of 3,5-dimethylphenylboronic acid, 0.3 g (0.58 mmol, 1 mol.%) of Pd(P^tBu3)2, 18.7 g of Na2CO3, 100 ml of 2-methyltetrahydrofurane, and 90 ml of water was refluxed for 5 h. Then 200 ml of water was added, the organic layer was separated, and the aqueous layer was extracted with 2x100 ml of dichloromethane. The combined organic extract was dried over K2CO3 and then evaporated to dryness. The crude product was dissolved in 50 ml of dichloromethane, and 75 ml of hexane was added. Most of dichloromethane was evaporated, and the precipitated title product was filtered off (G3) and dried under vacuum to give 14.7 g (78.5%) of a white solid mass. ¹H NMR (CDCl₃): δ 7.27 (s, 1H), 7.04 (br.s, 1H), 6.96 (br.s, 2H), 4.29-4.24 (m, 4H), 3.02 (dd, J = 17.6 Hz, J = 8.1 Hz, 1H), 2.55-2.46 (m, 2H), 2.38 (s, 6H), 1.97-1.87 (m, 1H), 1.52-1.41 (m, 1H), 0.94 (t, J = 7.4 Hz, 3H). ¹³C NMR (CDCl₃): δ 207.91, 146.78, 146.38, 143.90, 137.84, 134.31, 129.91, 129.48, 128.36, 127.20, 110.58, 64.77, 63.64, 48.84, 31.36, 24.55, 21.40, 11.61. 5-(3,5-Dimethylphenyl)-7-ethyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxine NaBH4 (2.58 g, 68.3 mmol, 1.5 equiv.) was added to a solution of 9-(3,5-dimethylphenyl)-7- ethyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (14.7 g, 45.5 mmol) in 190 ml of THF cooled to 5 °C. To this mixture, 70 ml of MeOH was added dropwise for ca.5 h at 5 °C, and the resulting mixture was stirred overnight at room temperature. Then, this mixture was evaporated to dryness, 150 ml of dichloromethane and 300 ml water were added to the residue, and the so obtained mixture was acidified with 2 M HCl to pH~6.5. The organic layer was separated, the aqueous layer was additionally extracted with 2x50 ml of dichloromethane. The combined organic extract was evaporated to dryness to give a white solid mass. This mass was dissolved in 300 ml of toluene and heated to ca.60 °C, then 0.5 g of TsOH was added to it. This mixture was refluxed with Dean-Stark head for 10 min. Then, the reaction mixture was quickly cooled to room temperature using an ice-water bath. The formed solution was washed with 10% K2CO3, the organic layer was separated, the aqueous layer was extracted with 100 ml of dichloromethane. The combined organic extract was dried over K2CO3, passed through a pad of silica gel 60 (40-63 µm), and then evaporated to dryness. The crude product was triturated with 40 ml of n-pentane, the precipitate was filtered off (G3) and dried under vacuum. This procedure gave 11.88 g (85.2%) of the title product as a white powder. ¹H NMR (CDCl₃): δ 7.02 (br.s, 2H), 6.98 (br.s, 1H), 6.78 (s, 1H), 6.38 (m, 1H), 4.23-4.21 (m, 2H), 4.19-4.17 (m, 2H), 3.10 (s, 2H), 2.40 (m, 2H), 2.36 (s, 6H), 1.14 (t, J = 7.4 Hz, 3H).¹³C NMR (CDCl3): δ 151.76, 142.47, 138.40, 137.52, 137.46, 136.38, 135.01, 128.93, 127.27, 124.36, 107.66, 64.39, 64.14, 40.42, 24.24, 21.40, 13.27. 7-Isopropyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one 2-isopropylacryloyl chloride (78.0 g, 588 mmol) was added dropwise over 15 min to a suspension of 82.3 g (617 mmol) of AlCl3 in 500 ml of dichloromethane cooled to –78 °C, followed by dropwise addition of benzo-1,4-dioxane (80.05 g, 588 mmol). The temperature of the reaction mixture was raised to room temperature in 1 h, then the reaction mixture was stirred for 19 h at room temperature. The resulting mixture was poured onto 1500 cm³ of crushed ice. The organic layer was separated, the aqueous layer was extracted with 2x200 ml of dichloromethane. The combined organic extract was washed with aqueous K₂CO₃, dried over K2CO3 and passed through a short pad of silica gel 60 (40-63 µm), which was additionally washed with 200 ml of dichloromethane. The combined organic elute was evaporated to dryness. The residue was washed with 300 ml of n-hexane and dried under vacuum to give 105.4 g (77.1%) of the title material as a white solid mass. ¹H NMR (CDCl3): δ 7.22 (s, 1H), 6.90 (s, 1H), 4.33-4.31 (m, 2H), 4.27-4.25 (m, 2H), 3.00 (dd, J = 17.1 Hz, J = 8.0 Hz, 1H), 2.79 (dd, J = 17.1 Hz, J = 3.8 Hz, 1H), 2.64-2.60 (m, 1H), 2.42- 2.32 (m, 1H), 1.03 (d, J = 6.9 Hz, 3H), 0.76 (d, J = 6.8 Hz, 3H).¹³C NMR (CDCl3): δ 207.40, 149.83, 148.14, 143.50, 131.19, 113.89, 111.37, 64.60, 63.82, 53.31, 29.04, 27.39, 20.86, 17.02. 9-Bromo-7-isopropyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one A mixture of 51.1 g (220 mmol) of 7-isopropyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin- 6-one, 67.0 g of NaOAc, 1.8 g of ⁿBu₄NBr, 200 ml of dichloromethane, and 400 ml of water was cooled to +5 °C, and then bromine (11.3 ml, 35.15 g, 220 mmol) was added dropwise over 20 min at this temperature. The resulting mixture was stirred for 1 h at this temperature, then a solution of 16.4 g of NaOAc in 100 ml of water was added, and finally bromine (2.6 ml, 8.0 g, 50 mmol) was added over 10 min. This mixture was stirred for 1 h at 5 °C, then the resulting mixture was washed with aqueous Na₂SO₃ to remove excess bromine. The organic layer was separated, and the aqueous layer was additionally extracted with 2x200 ml of dichloromethane. The combined organic extract was filtered through a pad of silica gel 60 (40- 63 µm), which was additionally washed with 200 ml of dichloromethane. The combined organic elute was evaporated to dryness. The crude product was purified by flash chromatography on silica gel 60 (40-63 µm, d 50 mm, l 1000 mm, eluent: dichloromethane). Yield 37.2 g (54.3%). ¹H NMR (CDCl3): δ 7.20 (s, 1H), 4.46-4.44 (m, 2H), 4.30-4.28 (m, 2H), 3.00 (dd, J = 17.5 Hz, J = 8.0 Hz, 1H), 2.75 (dd, J = 17.5 Hz, J = 3.8 Hz, 1H), 2.66 (m, 1H), 2.39 (m, 1H), 1.05 (d, J = 6.9 Hz, 3H), 0.77 (d, J = 6.8 Hz, 3H).¹³C NMR (CDCl₃): δ 206.84, 147.82, 146.57, 144.09, 131.34, 110.44, 108.98, 65.29, 63.61, 53.07, 29.05, 28.79, 20.73, 17.06. 9-(3,5-Dimethylphenyl)-7-isopropyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one A mixture of 37.2 g (119.6 mmol) of 9-bromo-7-isopropyl-2,3,7,8-tetrahydro-6H-indeno[5,6- b][1,4]dioxin-6-one, 22.78 g (151.9 mmol, 1.27 equiv.) of 3,5-dimethylphenylboronic acid, 0.61 g (1.2 mmol, 1 mol.%) of Pd(P^tBu3)2, 38.5 g of Na2CO3, 200 ml of 2-methyltetrahydrofurane, and 180 ml of water was refluxed for 2 h. Then, 400 ml of water was added, the organic layer was separated, and the aqueous layer was extracted with 2x200 ml of dichloromethane. The combined organic extract was dried over K2CO3 and then evaporated to dryness. The product was isolated by flash chromatography on silica gel 60 (40-63 µm, d 50 mm, l 500 mm, eluent: dichloromethane, then, dichloromethane:ether = 1:10, vol.). This procedure gave 37.4 g (93%) of the title product as a white powder. ¹H NMR (CDCl3): δ 7.26 (s, 1H), 7.05 (br.s, 1H), 6.96 (br.s, 2H), 4.30-4.23 (m, 4H), 2.85 (dd, J = 18.1 Hz, J = 8.6 Hz, 1H), 2.60-2.54 (m, 2H), 2.39 (s, 6H), 2.39-2.32 (m, 1H), 0.97 (d, J = 6.9 Hz, 3H), 0.75 (d, J = 6.8 Hz, 3H).¹³C NMR (CDCl3): δ 207.75, 146.72, 143.83, 137.83, 134.36, 130.59, 129.46, 128.30, 127.19, 110.35, 64.74, 63.61, 53.12, 29.02, 27.09, 21.39, 20.83, 17.15. 5-(3,5-Dimethylphenyl)-7-isopropyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxine NaBH4 (6.35 g, 168.0 mmol, 1.5 equiv.) was added to a solution of 9-(3,5-dimethylphenyl)-7- isopropyl-2,3,7,8-tetrahydro-6H-indeno[5,6-b][1,4]dioxin-6-one (37.4 g, 111.2 mmol) in 380 ml of THF cooled to 5 °C. To this mixture, 140 ml of MeOH was added dropwise over ca.5 h at 5 °C, and the resulting mixture was stirred overnight at room temperature. Then, this mixture was evaporated to dryness, 500 ml of dichloromethane and 1000 ml water were added to the residue, and the so obtained mixture was acidified with 2 M HCl to pH~6.5. The organic layer was separated, the aqueous layer was additionally extracted with 2x50 ml of dichloromethane. The combined organic extract was evaporated to dryness to give a white solid mass, which was dissolved in 500 ml of toluene, preheated to ca.60 °C, then 1.0 g of TsOH was added. This mixture was refluxed with Dean-Stark head for 10 min. Then, the reaction mixture was quickly cooled to room temperature using an ice-water bath. The formed solution was washed with 10% K2CO3, the organic layer was separated, and the aqueous layer was extracted with 100 ml of dichloromethane. The combined organic extract was dried over K₂CO₃, passed through a pad of silica gel 60 (40-63 µm), and then evaporated to dryness. The crude product was triturated with 50 ml of n-hexane, the precipitate was filtered off (G3), the filter cake was washed with 20 ml of n-hexane and dried under vacuum. This procedure gave 31.8 g (89%) of the title product as a white powder. ¹H NMR (CDCl3): δ 7.02 (br.s, 2H), 6.99 (br.s, 1H), 6.79 (s, 1H), 6.38 (m, 1H), 4.22-4.20 (m, 2H), 4.18-4.16 (m, 2H), 3.11 (s, 2H), 2.66 (sep, J = 6.8 Hz, 1H), 2.36 (s, 6H), 1.14 (d, J = 6.9 Hz, 6H).¹³C NMR (CDCl3): δ 156.37, 142.49, 138.21, 137.57, 137.48, 136.38, 134.87, 128.95, 127.31, 127.27, 123.28, 107.78, 64.39, 64.12, 38.59, 30.01, 22.52, 21.41. Synthesis of MC-IE3 Bis[9-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxin-6-yl] dimethylsilane ⁿBuLi in hexane (2.5 M, 16.0 ml, 40.0 mmol) was added in one portion to a solution of 11.7 g (40.0 mmol) of 5-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxin in a mixture of 200 ml of ether and 10 ml of THF at –50 °C. This mixture was stirred overnight at room temperature, then the resulting yellow solution was cooled to –50 °C, and 150 mg of CuCN was added. The obtained mixture was stirred for 15 min at –20 °C, and then 2.58 g (20.0 mmol) of dichlorodimethylsilane was added in one portion. This mixture was stirred for 4 h at room temperature, then filtered through a pad of silica gel 60 (40-63 µm) which was additionally washed with 2x40 ml of ether. The combined yellowish organic elute was evaporated to dryness, and the residue was dried in vacuum at elevated temperature to give 12.66 g (ca.98.8%, purity ca. 75%) of the title product (a ca. 55:45 mixture of the stereoisomers) as a slightly yellowish glass which was used without further purification. Anti-dimethylsilanediyl-bis[9-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-indeno[5,6- b][1,4]dioxin-6-yl]zirconium dichloride ⁿBuLi in hexanes (2.5 M, 14.0 ml, 35.0 mmol) was added in one portion at room temperature to a solution of 11.18 g (17.45 mmol) of bis[9-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-6H- indeno[5,6-b][1,4]dioxin-6-yl]dimethylsilane in 110 ml of di-n-butyl ether. This mixture was stirred for 4.5 h at room temperature, then the resulting red solution was cooled to 0 °C in an ice-bath, and ZrCl4 (4.07 g, 17.47 mmol) was added. The reaction mixture was stirred for 24 h at room temperature to give a red suspension. This suspension was evaporated to dryness, and the formed solid was extracted with 150 ml of boiling toluene. On the evidence of NMR spectroscopy, the obtained extract included a ca.64:36 mixture of rac- and meso-zirconocene dichlorides. The filter cake included meso-zirconocene dichloride. The latter precipitate was extracted with 4x50 ml of boiling toluene. The obtained extract was evaporated to ca.20 ml, and 20 ml of hexane was added. The red crystalline solid precipitated from this solution at room temperature was collected and then dried in vacuum. This procedure gave 1.2 g (8.5%) of meso-zirconocene dichloride. The above-obtained toluene solution (after very first filtration) was evaporated to ca.80 ml. The orange solid precipitated from this hot solution was collected and dried under vacuum. This procedure gave 1.72 g of rac-zirconocene dichloride containing 0.8 mol of toluene per mol of the complex. Meso-zirconocene dichloride: Anal. calc. for C₄₂H₄₂Cl₂O₄SiZr^.: C, 62.98; H, 5.29. Found: C, 63.25; H, 5.52.¹H NMR (CDCl₃): δ 7.14 (br.s, 4H), 7.05 (s, 2H), 6.94 (s, 2H), 6.39 (s, 2H), 4.25-4.17 (m, 4H), 4.14-4.06 (m, 4H), 2.33 (s, 12H), 2.32 (s, 6H), 1.35 (s, 3H), 1.16 (s, 3H). ¹³C NMR (CDCl₃): δ 144.25, 142.74, 137.35, 135.15, 134.66, 132.69, 129.22, 127.69, 122.88, 121.54, 118.88, 110.74, 80.90, 64.56, 64.06, 21.46, 18.78, 2.71, 2.37. Rac-zirconocene dichloride: Anal. calc. for C₄₂H₄₂Cl₂O₄SiZr*0.8C₇H₈: C, 65.36; H, 5.58. Found: C, 65.30; H, 5.76.¹H NMR (CDCl₃): δ 7.23 (br.s, 4H), 7.00 (s, 2H), 6.96 (s, 2H), 6.58 (s, 2H), 4.30-4.17 (m, 8H), 2.33 (s, 12H), 2.21 (s, 6H), 1.22 (s, 6H).¹³C NMR (CDCl3): δ 145.21, 143.58, 137.47, 134.45, 134.27, 130.22, 129.26, 127.73, 122.46, 121.43, 120.89, 108.68, 79.31, 64.55, 64.31, 21.38, 18.51, 2.39. Synthesis of MC-IE4 Bis[9-(3,5-dimethylphenyl)-7-ethyl-2,3-dihydro-6H-indeno[5,6-b][1,4]dioxin-6-yl]dimethyl silane To a suspension of 11.7 g (38.18 mmol) of 5-(3,5-dimethylphenyl)-7-ethyl-2,3-dihydro-6H- indeno[5,6-b][1,4]dioxin in a mixture of 200 ml of ether and 50 ml of THF 15.2 ml (38.18 mmol) of 2.5 M ⁿBuLi in hexanes was added in one portion at -50^oC. This mixture was stirred overnight at room temperature, then the resulting yellow suspension was cooled to -50°C, and 200 mg of CuCN was added. The obtained mixture was stirred for 15 min at -20^oC, and then 2.46 g (19.09 mmol) of dichlorodimethylsilane was added in one portion. This mixture was stirred overnight at room temperature and then evaporated to dryness. The crude product was dissolved in a mixture of 50 ml of dichloromethane and 50 ml of hexane and then filtered through a pad of silica gel 60 (40-63 um) which was additionally washed by 2x40 ml of dichloromethane. The combined organic elute was evaporated to dryness, and the residue was dried in vacuum at elevated temperature to give 12.9 g (ca. quantitative yield, purity ca. 91%) of the title product (as a ca.55:45 mixture of the stereoisomers) as a white powder which was used without further purification. Rac-dimethylsilanediyl-bis[9-(3,5-dimethylphenyl)-7-ethyl-2,3-dihydro-indeno[5,6- b][1,4]dioxin-6-yl]zirconium dichloride To a solution of 12.9 g (ca.19.09 mmol) of bis[9-(3,5-dimethylphenyl)-7-ethyl-2,3-dihydro-6H- indeno[5,6-b][1,4]dioxin-6-yl](dimethyl)silane in 110 ml of di-n-butyl ether, 15.3 ml (38.2 mmol) of 2.5 M ⁿBuLi in hexanes was added in one portion at – 20ºC. This mixture was stirred for 4.5 h at room temperature, then the resulting yellow suspension was cooled to 0^oC, and 4.45 g (19.09 mmol) of ZrCl4 was added. The reaction mixture was stirred for 24 h at room temperature to give an orange suspension. This suspension was evaporated to dryness, the formed solid was extracted with 400 ml of the boiling toluene. On the evidence of NMR spectroscopy, the obtained extract included a ca.55:45 mixture of rac- and meso-zirconocene dichlorides. The filter cake (ca. 1.9 g) included meso-zirconocene dichloride. The red precipitate fallen from above-obtained mother liquor overnight at room temperature was collected and dried in vacuum. This procedure gave 3.5 g of meso-zirconocene dichloride containing 1 mol of toluene per mol of the complex. The mother liquor was evaporated to ca. 120 ml. The orange crystalline precipitate fallen from this solution at room temperature was collected and dried in vacuum. This procedure gave 0.56 g of rac-zirconocene dichloride containing 1 mol of toluene per mol of the complex. The mother liquor was evaporated to ca. 50 ml. The orange crystalline precipitate fallen from this solution at room temperature was collected. This procedure gave 4.3 g of a ca. 92:8 mixture of rac- and meso-zirconocene dichlorides, which was recrystallized from 50 ml of toluene. The orange crystalline solid precipitated from this solution at room temperature was collected and dried under vacuum. This procedure gave 3.35 g of rac-zirconocene dichloride containing 1 mol of toluene per mol of the complex. Meso-zirconocene dichloride: Anal. calc. for C₄₄H₄₆Cl₂O₄SiZr*C₇H₈: C, 66.50; H, 5.91. Found: C, 66.71; H, 6.18.¹H NMR (CDCl₃): δ 7.16 (br.s, 4H), 7.07 (s, 2H), 6.94 (s, 2H), 6.42 (s, 2H), 4.25-4.17 (m, 4H), 4.12-4.06 (m, 4H), 2.62 (m, 4H), 2.33 (s, 12H), 1.37 (s, 3H), 1.17-1.13 (m, 9H). ¹³C NMR (CDCl₃): δ 144.34, 142.78, 142.27, 137.33, 134.68, 132.74, 129.17, 127.74, 123.09, 121.62, 116.99, 110.82, 79.55, 64.57, 64.07, 26.27, 21.46, 17.69, 2.76, 2.70. rac-zirconocene dichloride: Anal. calc. for C₄₄H₄₆Cl₂O₄SiZr*C₇H₈: C, 66.50; H, 5.91. Found: C, 66.63; H, 6.06. ¹H NMR (CDCl3): δ 7.25 (br.s, 4H), 6.98 (s, 2H), 6.96 (s, 2H), 6.62 (s, 2H), 4.29-4.15 (m, 8H), 2.69 (m, 2H), 2.41 (m, 2H), 2.33 (s, 12H), 1.22 (s, 6H), 1.07 (t, J = 7.4 Hz, 3H). ¹³C NMR (CDCl3): δ 145.28, 143.51, 141.58, 137.43 (br. s), 134.47, 130.23, 129.20, 127.80, 122.51, 121.54, 118.86, 108.78, 78.00, 64.53, 64.29, 25.91, 21.37, 17.46, 2.73. Catalyst Preparations All catalysts were prepared using silica Sunspera AGC DM-L-303, calcined at 600 °C. MAO Axion CA1330 was used as received and stored at –20 °C not longer than 6 months. The catalysts were prepared by following a two-step preparation method. First step is the preparation of SiO2/MAO (activated carrier), followed by a second step where a toluene solution of the metallocene complex is impregnated on the dry support from the first step. Only in case the metallocene is not enough soluble in toluene, a second aliquot of MAO is added to the metallocene/toluene slurry in order to promote the full dissolution of the metallocene. Preparation of SiO2/MAO activated carrier A steel reactor equipped with a mechanical stirrer and a filter net was flushed with nitrogen. 10 kg of SiO2 carrier was first added from a feeding drum into the reactor, followed by careful pressurizing and depressurizing with nitrogen. Then, toluene (43.5 kg) was added. The SiO2/toluene slurry was stirred for 25 min at 22 °C. Then, 18 kg of 30 wt% MAO in toluene (Axion CA 1330) was added slowly (140 min) through a 12 mm line on the top of the reactor keeping the temperature around 22 °C. After MAO addition, the reactor temperature was quickly increased to 90 °C and the mixture was stirred at this temperature for 120 min. Then the hot toluene was filtered out and the solid cake was washed twice with hot toluene while stirring (43.5 kg, 90 °C, 30 min, 40 rpm). Each time the hot toluene was filtered out. Finally the solid cake was dried with slow stirring (5 rpm) under vacuum for 9 h at 80 °C. Synthesis of catalyst SiO₂/MAO/MC-CE1, comparative catalyst 1 (CE1) In a nitrogen filled glovebox, dry toluene (2.1 mL) was added to an aliquot of metallocene MC- CE1 (43.1 mg, purity 97.1 %, impurity being n-hexane). The mixture was stirred for 30 minutes at room temperature. Next, 2.0 g of the silica/MAO carrier was placed in a glass vial. The solution of metallocene in toluene was added dropwise by means of a syringe to the SiO₂/MAO carrier over the course of 5 minutes with gentle mixing. The resulting mixture was shaken well and allowed to stay for 1 hour. The resulting solid was dried in vacuum for 1 hour at 60°C to yield the catalyst as red free flowing powder Synthesis of catalyst SiO₂/MAO-MC-IE1/MAO, SMLO084, illustrative catalyst 1 (IE1) In a nitrogen filled glovebox, dry toluene (2.3 mL) and MAO solution (0.2 mL) were added to 23.8 mg of rac-dimethylsilanediyl-bis[2-methyl-4-(3,5-di-methylphenyl)-5-methoxy-6-tert- butyl-inden-1-yl)zirconium dichloride (metallocene MC-IE1) placed in a septum bottle. The solution was stirred for 60 minutes at room temperature. Next, 2.0 g of SiO2/MAO was placed in a septum bottle. The solution of metallocene in toluene was added dropwise by means of a syringe to the SiO2/MAO carrier over the course of 5 minutes with gentle mixing. The resulting powder was allowed to rest for 1 hour, then it was transferred into a Schlenk flask and dried under vacuum for 1 hour at 60 °C to yield the catalyst as a red free-flowing powder. Synthesis of SiO2/MAO-MC-IE2, SMLQ081, illustrative catalyst 2 (IE2) In a nitrogen filled glovebox, dry toluene (2.5 mL) was added to 26.3 mg of metallocene rac- dimethylsilanediylbis[2-ethyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butyl-inden-1-yl] zirconium dichloride (metallocene MCIE-2) placed in a septum bottle. The mixture was stirred for 30 minutes at room temperature. Next, 2.0 g of SiO2/MAO was placed in a septum bottle. The solution of metallocene in toluene was added dropwise by means of a syringe to the SiO2/MAO carrier over the course of 5 minutes with gentle mixing. The resulting powder was allowed to rest for 1 hour and then it was transferred into a Schlenk flask and dried under vacuum for 1 hour at 60 °C to yield the catalyst as a salmon-red, free-flowing powder. Synthesis of SiO2/MAO-MC-IE3/MAO, SMQ082, inventive catalyst 3 (IE3) In a nitrogen filled glovebox, dry toluene (2.5 mL) was added to 24.0 mg of metallocene MC- IE3 placed in a septum bottle. The mixture was stirred for 30 minutes at room temperature and then, to facilitate metallocene dissolution, 0.1 mL of a 30 wt% MAO solution in toluene (Axion CA1330) was added and stirring continued for additional 30 min at room temperature. Next, 2.0 g of the silica/MAO carrier was placed in a glass vial. The solution of metallocene in toluene was added dropwise by means of a syringe to the SiO₂/MAO carrier over the course of 5 minutes with gentle mixing. The resulting mixture was shaken well and allowed to stay for 1 hour. The resulting solid was dried under vacuum for 1 hour at 60°C to yield the catalyst as a light red, free-flowing powder. Synthesis of SiO2/MAO-MC-IE4/MAO, SMLQ123, inventive catalyst 4 (IE4) In a nitrogen filled glovebox, dry toluene (2.7 mL) was added to 24.9 mg of metallocene MC- IE4 placed in a septum bottle. The mixture was stirred for 30 minutes at room temperature and then, to facilitate metallocene dissolution, 0.1 mL of a 30 wt% MAO solution in toluene (Axion CA1330) was added and stirring continued for additional 30 min at room temperature. Next, 2.0 g of the silica/MAO carrier was placed in a glass vial. The solution of metallocene in toluene was added dropwise by means of a syringe to the SiO₂/MAO carrier over the course of 5 minutes with gentle mixing. The resulting mixture was shaken well and allowed to stay for 1 hour. The resulting solid was dried under vacuum for 1 hour at 60°C to yield the catalyst as a pink-brown, free-flowing powder The metallocene content in each catalyst is calculated from mass balance. The values are listed in table 1: Table 1: catalysts tested and their metallocene content a^b Al in Al MC in catalyst Catalyst atalyst ^c Al/Zr in catalyst c wt% wt% wt% molar CE1 12,7 1,56 12,7 401 IE1 13,3 1,14 14,3 513 IE2 12,3 1,30 n.m. 311 IE3 12,3 1,15 12,8 484 IE4 12,4 1,21 n.m. 315 a) Al content of the SiO2/MAO carrier measured by ICP; b) MC=metallocene; metallocene content in the dry catalyst calculated from mass balance c) Al content of the catalyst measured by ICP Polymer analysis MFR MFR were measured on the Schmelz-Index-Prüfgerät MI-4 (Göttfert Werkstoff-Prüfmaschinen GmbH) at 230°C with a loading of 2.16 kg (MFR₂) according to DIN ISO 1133 and is indicated in g/10 min. DSC The DSC curves and data have been produced on a DSC Q200 TA Instrument, by placing a 5-7 mg sample cut from the polymer MFR string, into a closed DSC aluminum pan, heating the sample from -10 °C to 225 °C at 10 °C/min, holding for 10 min at 225 °C, cooling from 225 °C to –30 °C, holding for 5 min at –30 °C, heating from –30 °C to 225 °C at 10 °C/min. The reported T_m values are those of the peak of the endothermic heat flow determined from the second heating scan. GPC The MWD and the corresponded molecular weight averages M_n, M_w, M_v and M_z of the polymer sample were determined by using Gel Permeation Chromatography (GPC) at 160°C. All samples were integrated at the low Mw end up to the 3^rd last calibration point of the calibration curve (PS = 1820 g/mol ~ 1340 g/mol PP equivalent). A high temperature GPC equipped with a suitable concentration detector (like IR5 or IR4 from PolymerChar (Valencia, Spain), an online four capillary bridge viscometer (PL-BV 400-HT), and a dual light scattering detector (PL-LS 15/90 light scattering detector) with a 15° and 90° angle was used. 3x Olexis and 1x Olexis Guard columns from Agilent as stationary phase and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/L 2,6-Di tert butyl-4-methyl-phenol) as mobile phase at 160 °C and at a constant flow rate of 1 mL/min was applied. 200 μL of sample solution were injected per analysis. All samples were prepared by dissolving 8.0 – 10.0 mg of polymer in 10 mL (at 160 °C) of stabilized TCB (same as mobile phase) for 2,5 hours at 160°C under continuous gentle shaking. The injected concentration of the polymer solution at 160 °C (c160°C) was determined in the following way. ^_{^^^°^ = ^^^} _{^ ∗ 0,8772} _^^ With: w25 (polymer weight) and V25 (Volume of TCB at 25°C). The column set was calibrated using universal calibration (according to ISO 16014-2:2019) with 19 narrow MWD polystyrene (PS) standards in the range of 0.5 kg/mol to 11500 kg/mol. The PS standards were dissolved at 160°C for 15 min or alternatively at room temperatures at a concentration of 0.2 mg/ml for molecular weight higher and equal 899 kg/mol and at a concentration of 1 mg/ml for molecular weight below 899 kg/mol. The conversion of the polystyrene peak molecular weight to polypropylene molecular weights is accomplished by using the Mark Houwink equation and the following Mark Houwink constants: KPS = 19 x 10^-5 ml/g, αPS = 0.655 KPP = 39 x 10^-5 ml/g, αPE = 0.725 A third order polynomial fit was used to fit the calibration data. All samples were prepared in the concentration range of 0.5 -1 mg/ml and dissolved at 160 °C for 3 hours under continuous gentle shaking. Molecular weight averages (M_n, M_w, M_v and M_z), Molecular weight distribution (MWD) and its broadness, described by the polydispersity index PD= Mw/Mn (wherein Mn is the number average molecular weight and M_w is the weight average molecular weight) were determined using the following formulas: Description of microstructure quantification by NMR spectroscopy Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers. Quantitative ¹³C{¹H} NMR spectra recorded in the molten-state using a Bruker Avance III 500 NMR spectrometer operating at 500.13 and 125.76 MHz for ¹H and ¹³C respectively. All spectra were recorded using a ¹³C optimised 7 mm magic-angle spinning (MAS) probehead at 180°C using nitrogen gas for all pneumatics. Approximately 200 mg of material was packed into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity needed for rapid identification and accurate quantification {as described in Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys.2006;207:382; Parkinson, M., Klimke, K., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys.2007;208:2128; Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373}. Standard single-pulse excitation was employed utilising the NOE at short recycle delays of 3 s {as described in Pollard, M., Klimke, K., Graf, R., Spiess, H.W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004;37:813; Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2006;207:382} and the RS-HEPT decoupling scheme {Filip, X., Tripon, C., Filip, C., J. Mag. Resn.2005, 176, 239, Griffin, J.M., Tripon, C., Samoson, A., Filip, C., and Brown, S.P., Mag. Res. in Chem.200745, S1, S198}. A total of 16384 (16k) transients were acquired per spectra. Quantitative ¹³C{¹H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals. All chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm. Characteristic signals corresponding to the incorporation of 1-butene were observed {A.J. Brandolini, D.D. Hills, “NMR spectra of polymers and polymer additives”, Marcel Deker Inc., 2000} and the comonomer content quantified. The amount of isolated 1-butene incorporated in PBP sequences was quantified using the integral of the αB2 sites at 43.6 ppm accounting for the number of reporting sites per comonomer: B = IαB2 / 2 The amount of consecutively incorporated 1-butene in PBBP sequences was quantified using the integral of the ααB2B2 site at 40.5 ppm accounting for the number of reporting sites per comonomer: BB = 2 * IααB2B2 In presence of BB the value of B must be corrected for the influence of the αB2 sites resulting from BB: B = (IαB2 / 2) – BB/2 The total 1-butene content was calculated based on the sum of isolated and consecutively incorporated 1-butene: Btotal = B + BB Characteristic signals corresponding to the incorporation of ethylene were observed {A.J. Brandolini, D.D. Hills, “NMR spectra of polymers and polymer additives”, Marcel Deker Inc., 2000} and the comonomer content quantified. The amount of isolated ethylene incorporated in PEP sequences was quantified using the integral of the Sββ sites at 24.3 ppm accounting for the number of reporting sites per comonomer: E = I_Sββ If characteristic signals corresponding to consecutive incorporation of ethylene in PEE sequence was observed the Sβδ site at 27.0 ppm was used for quantification: EE = I_Sβδ Characteristic signals corresponding to regio defects were observed {resconi00}. The presence of isolated 2,1-erythro regio defects was indicated by the presence of the two methyl sites at 17.7 and 17.2 ppm, by the methylene site at 42.4 ppm and confirmed by other characteristic sites. The presence of 2,1 regio defect adjacent an ethylene unit was indicated by the two inequivalent Sαβ signals at 34.8 ppm and 34.4 ppm respectively and the Tγγ at 33.7 ppm. The amount of isolated 2,1-erythro regio defects (P21e isolated) was quantified using the integral of the methylene site at 42.4 ppm (Ie9): P21e isolated = Ie9 If present the amount of 2,1 regio defect adjacent to ethylene (PE21) was quantified using the methine site at 33.7 ppm (ITγγ): PE21 = ITγγ The total ethylene content was then calculated based on the sum of ethylene from isolated, consecutively incorporated and adjacent to 2,1 regio defects: Etotal = E + EE + PE21 The amount of propene was quantified based on the Sαα methylene sites at 46.7 ppm including all additional propene units not covered by Sαα e.g. the factor 3*P21e isolated accounts for the three missing propene units from isolated 2,1-erythro regio defects: Ptotal = ISαα + 3*P21e isolated + B + 0.5*BB + E + 0.5*EE + 2*PE21 The total mole fraction of 1-butene and ethylene in the polymer was then calculated as: fB = Btotal / ( Etotal + Ptotal + Btotal ) fE = Etotal / ( Etotal + Ptotal + Btotal ) The mole percent comonomer incorporation was calculated from the mole fractions: B [mol%] = 100 * fB E [mol%] = 100 * fE The weight percent comonomer incorporation was calculated from the mole fractions: B [wt%] = 100 * ( fB * 56.11 ) / ( (fE * 28.05) + (fB * 56.11) + ((1-(fE+fB)) * 42.08) ) E [wt%] = 100 * ( fE * 28.05 ) / ( (fE * 28.05) + (fB * 56.11) + ((1-(fE+fB)) * 42.08) ) The mole percent of isolated 2,1-erythro regio defects was quantified with respect to all propene: [21e] mol% = 100 * P_{21e isolated} / P_total The mole percent of 2,1 regio defects adjacent to ethylene was quantified with respect to all propene: [E21] mol% = 100 * P_E21 / P_total The total amount of 2,1 defects was quantified as following: [21] mol% = [21e] + [E21] Characteristic signals corresponding to other types of regio defects (2,1-threo, 3,1 insertion) were not observed {Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev.2000, 100, 1253}. Monomers and gases Hydrogen (quality 6.0) was supplied by Air Liquide and used as received. Propylene, quality 2.3, and butene have been purified by passing through columns filled with PolyMax301 T- 4427B (60°C; Cu/CuO), Molecular sieve MS13X-APG 1/16 and Selexsorb COS 1/8. Propylene/butene/ethylene terpolymerization procedure (liquid monomer, 20 L BSR) A stainless-steel reactor equipped with a ribbon stirrer, and a total volume of 20.9 dm³ containing 0.2 bar-g propylene, is filled with additional 3.88 kg propylene from a balance. Triethylaluminium (0.8 ml of 0.62 molar solution in n-heptane) is added using a stream of 250 g propylene. Then the chosen amount of H2 is added via mass flow controller in one minute. The reactor temperature is stabilized at the desired temperature of the prepolymerization step by using a thermostat. The solution is stirred at 250 rpm for at least 20 min. Then the catalyst is injected as described in the following. The desired amount of catalyst (solid or as oil slurry) is loaded into a stainless-steel vial in a glovebox. Then the catalyst vial is mounted on a port on the lid of the reactor. The catalyst is fed into the reactor by flushing 350 g propylene from the balance through the catalyst vial. Stirring speed is kept at 250 rpm and pre-polymerization is run for the set time and temperature. At the end of the prepolymerization step (prepoly step), ethylene and butene (and, if needed, a second aliquot of H₂) are added in ~1-2 min by using MFCs while the polymerization temperature is increased to the target value. Afterwards the reactor temperature is kept constant throughout the polymerization. The polymerization time is measured starting when the temperature is 2 °C below the set polymerization temperature. When the set time has lapsed, the reaction is stopped by injecting 5 ml ethanol, cooling the reactor and simultaneously flashing the volatile components. After purging the reactor 3 times with N2 and one vacuum/N2 cycle, the reactor is opened; the polymer powder is taken out and dried overnight in a fume hood.100 g of the polymer is additivated with 0.5 wt% Irganox B225 (dissolved in acetone) and then dried overnight in a fume hood and additionally one hour in a vacuum drying oven at 60°C. The butene amount required to reach the desired butene concentration in liquid phase at 70 °C and t=0 has been calculated by Aspen. 2-step propylene/butene/ethylene terpolymerization procedure (liquid monomer + gas phase, 20 L BSR) Step 1, polymerization in liquid monomers: like above Step 2, polymerization in gas phase. After the bulk step is completed, the stirrer speed is reduced to 50 rpm and the pressure is reduced to 0.4 bar-g by venting the monomers. Then the stirrer speed is set to 180 rpm, the reactor temperature to 70 °C and a given batch amount of ethylene was added to reach the desired comonomer ratio and pressure of 21 bar-g by feeding a C3/C2 gas mixture of composition defined by: C2/C3 is the weight ratio of the two monomers and R is their reactivity ratio, determined experimentally. In the present experiments, R=0.4. When the pressure reaches 20 °C bar-g, hydrogen is added via flow controller in 1 minute. The temperature is held constant by thermostat and the pressure of 21 bar-g is kept constant by feeding via mass flow controller a C2/C3 and C4/C3 gas mixture of composition corresponding to the target polymer composition, until the set duration for this step has lapsed. Then the reactor is cooled down to about 30°C and the volatile components flashed out. After purging the reactor 2 times with N2 and one vacuum/N2 cycle, the product is taken out and dried overnight in a fume hood.100 g of the polymer is additivated with 0.5 wt% Irganox B225 (solution in acetone) and dried overnight in a fume hood, followed by one hour in a vacuum drying oven at 60°C. Propylene/butene/ethylene terpolymerization results The catalyst performances were compared. Results are summarised in the following tables.

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Claims

CLAIMS 1. A process for producing a propylene copolymer resin, comprising polymerizing propylene and at least one C₄-C₁₀ alpha olefin comonomer and optionally ethylene in the presence of a polymerization catalyst comprising, (i) a metallocene complex of formula (I); (ii) a cocatalyst system comprising a cocatalyst comprising a group 13 element; and (iii) optionally a support; wherein the metallocene complex of formula (I) is wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently selected from C1-C20-hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form, together with the Si atom to which they are attached, a C4-C8 ring; R² and R²’ are each independently CH2-R²¹, with R²¹ being H or C1-C10- hydrocarbyl; n are each independently selected from an integer of from 1 to 5; each R³ and R⁴ is independently selected from H; C1-C10-hydrocarbyl; or -OR, -SR or -NR2, where R is C1-C10 hydrocarbyl; and/or wherein two adjacent R³ or two adjacent R⁴ form a ring together with the two C atoms of the phenyl ring to which they are bonded; R⁵ is C₁-C₁₀-hydrocarbyl, and R⁶ is OR⁸, where R⁸ is a C₁-C₁₀-hydrocarbyl; or S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial} R⁶ is OR⁹, wherein R⁵ and R⁹ form a C₃ to C₇ carbocycle together with the O groups and two C atoms of the phenyl ring to which the O groups of -OR⁵ and -OR⁹ are bonded; R⁵’ is C₁-C₁₀-hydrocarbyl and R⁶’ is OR⁸’, where R⁸’ is a C₁-C₁₀-hydrocarbyl; or R⁶’ is OR⁹’, wherein R⁵’ and R⁹’ form a C₃ to C₇ carbocycle together with the O groups and two C atoms of the phenyl ring to which the O groups of -OR⁵’ and -OR⁹’ are bonded; and R⁷ is H, Me, OMe, or C₆-C₂₀-aryl, whereby the C₆-C₂₀-aryl is optionally substituted 1 to 5 times with R³, whereby at least one R³ per said aryl group is not H.

2. A process as claimed in claim 1, wherein propylene is copolymerized with ethylene and a C4-C10 alpha olefin comonomer, wherein the C4-C10 alpha olefin comonomer is preferably butene.

3. A process as claimed in claim 1, which is a process for producing a propylene terpolymer resin, wherein said process comprises polymerizing propylene and at least two different C4-C10 alpha olefin comonomers.

4. A process as claimed in any one of the preceding claims, wherein: S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial} the metallocene complex has the formula (I–a): (I-a) wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently, same or different from each other, C₁-C₂₀- hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form, together with the Si atom they are attached to, a C₄-C₈ ring; R² and R^2’ are each independently, same or different from each other, CH₂-R²¹, with R²¹ being H or C₁-C₁₀-hydrocarbyl; R³ and R⁴ are each independently, same or different from each other, H, linear or branched C₁-C₆-alkyl, C₇-C₂₀-arylalkyl, C₇-C₂₀-alkylaryl, C₆-C₂₀aryl, or -OR³¹, with R³¹ being C₁-C₁₀-hydrocarbyl, whereby at least one R³ per present phenyl group and at least one R⁴ is not H; m are each independently, same or different from each other, an integer from 2 to 4; each R⁶¹ is independently, same or different from each other, -CH₂- , -CHR*-, or -C(R*)2- group, with R* being C1-C2-alkyl; R⁷ is H, Me, OMe, or C₆-C₂₀-aryl, whereby C₆-C₂₀-aryl is optionally substituted 1 to 5 times with R^3, whereby at least one R³ per said aryl group is not H. S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial}

5. A process as claimed in any one of the preceding claims, wherein R⁷ is H. S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial}

6. A process as claimed in any one of the preceding claims, wherein: the metallocene complex has the formula (I–c): (I-c) wherein: Mt is Zr or Hf; X is a sigma ligand; R¹ are each independently, same or different from each other, C₁-C₂₀- hydrocarbyl, optionally containing up to two heteroatoms of Group 14-16 of the Periodic Table, or form together with the Si atom they are attached to a C4-C8 ring; R² and R²’ are each independently, same or different from each other, CH2-R²¹, with R²¹ being H or linear or branched C1-6-alkyl; R³ and R⁴ are each independently, same or different from each other, H, linear or branched C1-C6-alkyl, C7-C20-arylalkyl, C7-C20-alkylaryl, C6-C20-aryl, or -OR³¹, with R³¹ being C1-C10-hydrocarbyl, whereby at least one R³ and at least one R⁴ is not H.

7. A process according to any of one of the preceding claims, wherein the complex is selected from: dimethylsilanediyl-bis[9-(3,5-dimethylphenyl)-7-methyl-2,3-dihydro-indeno[5,6- b][1,4]dioxin-6-yl]zirconium dichloride; and dimethylsilanediyl-bis[9-(3,5-dimethylphenyl)-7-ethyl-2,3-dihydro-indeno[5,6- b][1,4]dioxin-6-yl]zirconium dichloride. S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial}

8. A process as claimed in any one of the preceding claims, wherein the process comprises the steps of (I) in a first polymerization step, preferably in at least one slurry reactor, polymerizing propylene and at least one C₄-C₁₀ alpha olefin comonomer and optionally ethylene, preferably polymerizing propylene and butene, in the presence of the polymerization catalyst to produce a propylene copolymer matrix (A); and subsequently (II) in a second polymerization step, preferably in at least one gas phase reactor, polymerizing propylene and at least two different comonomers selected from ethylene and C4-C10 alpha olefin comonomers; more preferably ethylene and at least one C4- C10 alpha olefin comonomer, in the presence of the polymerization catalyst and the propylene copolymer matrix (A) from step (I) to produce a propylene terpolymer phase (B) dispersed in the propylene copolymer matrix (A).

9. A process as claimed in claim 8, wherein: (a) the first polymerization step is in at least one slurry reactor and the reaction temperature is in the range of 60 to 80^C, preferably 65 to 75°C; and/or (b) the second polymerization step is in at least one gas phase reactor and the reaction temperature is in the range of 60 to 100°C, preferably 70 to 90°C.

10. A process as claimed in claim 8 or claim 9, wherein: a) the propylene copolymer matrix (A) produced in step (I) is produced in an amount of less than or equal to 90 wt %, and b) the propylene terpolymer phase (B) produced in step (II) is produced in an amount of more than or equal to 10 wt %, of the total weight of the produced propylene terpolymer resin.

11. A process as claimed in any one claims 1 to 10, wherein the process is carried out in at least one slurry reactor, comprising the step of (I) polymerizing propylene and at least one C4-C10 alpha olefin comonomer and optionally ethylene, preferably polymerizing propylene and butene, in a slurry reactor to produce a propylene copolymer; and, preferably, (I) polymerizing propylene and at least two different comonomers selected from ethylene and C4-C10 alpha olefin comonomers; more preferably polymerizing propylene, ethylene and at least one C4-C10 alpha olefin comonomer in the slurry reactor to produce a propylene terpolymer. S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial}

12. A process as claimed in claim 11, wherein 50 to 99 wt% of the total weight of the propylene terpolymer resin end product is produced by the end of slurry step (I) and the process further comprises the step of: (II) transferring the reaction mixture of step (I) into a gas phase reactor for producing propylene terpolymer amounting to 1 to 50 wt% of the propylene terpolymer resin end product.

13. A process as claimed in any one of the preceding claims, wherein: (a) the process produces a propylene copolymer resin having a melt flow rate (230°C, 2.16 kg), MFR2, according to DIN ISO 1133 of 0.5 to 20 g/10min, preferably 1.0 to 10 g/10min, such as 2.0 to 8.0 g/10min; and/or (b) the propylene copolymer is a terpolymer having an ethylene content of 0.5 to 3.0 weight %, preferably 0.8 to 1.8 weight %; and/or (c) the propylene copolymer is a terpolymer having a C4-C10 alpha olefin comonomer content of 2.0 to 10 weight %, preferably 5.0 to 6.0 weight %.

14. A copolymer obtainable by the process as claimed in any one of the preceding claims. S_{ens Siteivnistyit:iv Citoyn:f Iindte nrntial}