WO1997042148A1

WO1997042148A1 - Cyclopentadiene compound substituted with cyclic groups

Info

Publication number: WO1997042148A1
Application number: PCT/NL1997/000206
Authority: WO
Inventors: Gerardus Johannes Maria Gruter; Johannes Antonius Maria Van Beek
Original assignee: Dsm N.V.
Priority date: 1996-05-03
Filing date: 1997-04-22
Publication date: 1997-11-13
Also published as: NL1003013C2; AU2578597A

Abstract

Polysubstituted cyclopentadiene compound wherein at least two substituents are cyclic alkyl groups, with the exception of di- and tricyclohexylcyclopentadiene and di(-1-methylcyclohexyl)-cyclopentadiene. Metal complexes in which at least one of these cyclopentadiene compounds is present as a ligand are useful as catalysts for the polymerisation of alpha-olefins.

Description

CYCLOPENTADIENE COMPOUND SUBSTITUTED WITH CYCLIC GROUPS

The invention relates to a polysubstituted cyclopentadiene compound. Cyclopentadiene compounds, both substituted and unsubstituted, are used widely as a starting material for preparing ligands in metal complexes having catalytic activity. In the great majority of cases, either unsubstituted cyclopentadiene or cyclopentadiene substituted with one to five methyl groups is used. Besides transition metals, lanthanides are also used as metals in these complexes.

In J. of Organomet. Chem., 479 (1994), 1-29 an overview is provided of the influence of the substituents on cyclopentadiene as a ligand in metal complexes. Here it is observed, on the one hand, that the chemical and physical properties of metal complexes can be varied over a wide range by the specific choice of the substituents on the cyclopentadiene ring. On the other hand, it is observed that no predictions can be made concerning the effect to be expected of specific substituents.

Hereinafter, cyclopentadiene will be abbreviated as Cp. The same abbreviation will be used for a cyclopentadienyl group if it is clear, from the context, whether cyclopentadiene itself or its anion is meant.

A drawback of the known substituted Cp compounds is that, while they do impart a certain stability to the complex when they are used as a ligand in a metal complex, at higher temperatures the stability of these complexes decreases faster than is desirable.

The object of the invention is to provide substituted Cp compounds which, when used as a ligand in a metal complex, give this complex a better resistance to higher temperatures than the known Cp compounds.

This object is achieved according to the invention in that at least two of the substituents are cyclic alkyl groups.

The presence of at least two cyclic alkyl groups instead of hydrogen or methyl groups appears to lead to a better resistance to higher temperatures than with other Cp compounds used as ligand. In US-A-3.255.267 di- and tricyclohexyl substituted Cp-compounds are described. Clark et al . J. Organometallic Chemistry, 462, (1993), 247-257 mentions di-(l-methylcyclohexyl ) substituted Cp-compounds. In these publications the better resistance to higher temperatuers of metal complexes comprising as a ligand a Cp-compound with at least two cyclic alkyl substituents is not mentioned nor suggested.

The cyclic alkyl groups may be the same as well as different. Besides the at least two cyclic alkyl groups required as substituent according to the invention, other groups may be substituted in the other positions of the Cp compound. These other substituents can be chosen from, for example, alkyl groups, linear as well as branched and cyclic ones, and alkenyl and aralkyl groups. It is also possible for these to contain, apart from carbon and hydrogen, one or more hetero atoms from groups 14-17 of the Periodic System of the Elements, for example 0, N, Si or F, a hetero atom not being bound directly to the Cp. For the Periodic System, see the new IUPAC notation to be found on the inside of the cover of the Handbook of Chemistry and Physics, 70th edition, 1989/1990. Examples of suitable groups are methyl, ethyl, (iso)propyl, secondary butyl, secondary pentyl, secondary hexyl and secondary octyl, (tertiary-)butyl and higher homologues, benzyl, phenyl, paratolyl. Substituted Cp compounds can, for instance, be prepared by reacting a halide of the substituting compound in a mixture of the Cp compound and an aqueous solution of a base in the presence of a phase transfer catalyst. The term Cp compounds refers to Cp itself and Cp already substituted in 1 to 3 positions, with the option of two substituents forming a closed ring. By means of the process according to the invention it is thus possible to convert unsubstituted compounds into mono- or polysubstituted ones, but it is also possible for mono- or polysubstituted compounds derived from Cp to be substituted further, ring closure also being included in the options. Use can be made of a virtually equivalent quantity with respect to the Cp-compound of the halogenated substituting compound. An equivalent quantity is understood to be a quantity in moles which corresponds to the desired substitution multiplicity, for example 2 moles per mole of Cp compound, if disubstitution with the substituent in question is intended. Depending on the size and the associated steric hindrance of the substituting compound it is possible to obtain trisubstituted to pentasubstituted Cp compounds. If a reaction with a tertiary halide of a substituting compound is carried out, as a rule only trisubstituted Cp compounds can be obtained, whereas with a primary and secondary halide of a susbtituting compound it is generally possible to achieve tetra- and often even pentasubstitution. Cyclic groups that are suitable as substituents are for instance cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclododecyl, cyclopent-2-enyl , cyclopent- 3-enyl, cyclohex-2-enyl , cyclohex-3-enyl , cyclohexa- 2,4-dienyl, cyclohept-2-enyl , cyclohept-3-enyl , cyclo- hept-4-enyl, cyclohepta-2-6-dienyl , cyclohepta-2 , 4 , 6- trienyl, cycloocta-2-enyl , cycloocta-4-enyl , cycloocta- 2,7-dienyl, cycloocta-2 , 6-dienyl , cyclonon-2-enyl , cy- clonona-2 , 8-dienyl and cyclonona-2 , 4 , 68-tetraenyl. Preferably, 2 , 3 of 4 cyclic alkyl groups are substituted in the Cp compound according to the invention. Besides these cyclic alkyls, any other groups mentioned above may be substituted in the Cp compound.

The substituents are preferably used in the process in the form of their halides, by preference in the form of their bromides. When bromides are used it appears that a smaller amount of phase transfer catalyst suffices and that a greater yield of the desired compound is achieved.

By means of this process it is also possible, without intermediate isolation or purification, to obtain Cp compounds which are substituted with specific combinations of substituents. Thus, for example, disubstitution with the aid of a certain halide of a substituting compound can first be carried out and in the same reaction mixture a third substitution with a different substituent, by adding a second, different halide of a substituting compound to the mixture after a certain time. This can be repeated, so that it is also possible to prepare Cp derivatives having three or more different substituents.

The substitution takes place in a mixture of the Cp compound and an aqueous solution of a base. The concentration of the base in the solution is in the range between 20 and 80 wt.%. Hydroxides of an alkali metal, for example K or Na, are highly suitable as a base. The base is present in an amount of 5-60, preferably 6-30 moles per mole of Cp compound. It was found that a substantial reduction of the reaction time can be achieved if the solution of the base is refreshed during the reaction, for instance by first mixing the solution with the other components of the reaction mixture and after some time isolating the aqueous phase and replacing it by a fresh portion of the solution of the base.

The substitution takes place at atmospheric or elevated pressure, for instance up to 100 MPa, the higher level being applied in particular if volatile components are present. The temperature at which the reaction takes place may vary within wide limits, for instance from -20 to 120°C, preferably between 10 and 50°C. Starting up the reaction at room temperature is usually suitable, after which the temperature of the reaction mixture can rise due to the heat released in the reaction. The substitution takes place in the presence of a phase transfer catalyst which is able to transfer OH-ions from the aqueous phase to the organic phase the OH-ions reacting in the organic phase with a H-atom which can be split off from the Cp compound. The organic phase contains the Cp compound and the substituting compound. As phase transfer catalyst use can be made of quaternary ammonium, phosphonium, arsonium, antimony, bismuthonium, and tertiary sulphonium salts. More preferably, ammonium and phosphonium salts are used, for example tricaprylmethylammonium chloride, commercially available under the name Aliquat 336 (Fluka AG, Switzerland? General Mills Co. , USA) and Adogen 464 (Aldrich Chemical Co., USA). Compounds such as benzyltriethylammonium chloride (TEBA) or benzyl- triethylammonium bromide (TEBA-Br), benzyltrimethyl- ammonium chloride, benzyltrimethylammonium bromide or benzyltrimethylammonium hydroxide (Triton B), tetra-n- butylammonium chloride, tetra-n-butylammonium bromide, tetra-n-butylammonium iodide, tetra-n-butylammonium hydrogen sulphate or tetra-n-butylammonium hydroxide and cetyltrimethylammonium bromide or cetyltri- methylammonium chloride, benzyltributyl-, tetra-n- pentyl-, tetra-n-hexyl- and trioctylpropylammonium chlorides and their bromides are likewise suitable. Usable phosphonium salts are, for example, tributyl- hexadecylphosphonium bromide, ethyltriphenylphosphonium bromide, tetraphenylphosphonium chloride, benzyltri- phenylphosphonium iodide and tetrabutylphosphonium chloride. Crown ethers and cryptands can also be used as a phase transfer catalyst, for example 15-crown-5, 18-crown-6, dibenzo-18-crown-6 , dicyclohexano-18-crown- 6, 4,7,13,16,21-pentaoxa-l, 10-diazabicyclo- [8.8.5]tricosane (Kryptofix 221), 4 , 7 , 13 , 18-tetraoxa- 1, 10-diazabicyclo[ 8.5.5]eicosane (Kryptofix 211) and 4,7,13,16 ,21,24-hexaoxa-l, 10-diazabicyclo[ 8.8.8]-hexa- cosane ("[2.2.2]") and its benzo derivative Kryptofix 222 B. Polyethers such as ethers of ethylene glycols can also be used as a phase transfer catalyst. Quaternary ammonium salts, phosphonium salts, phosphoric acid triamides, crown ethers, polyethers and cryptands can also be used on supports such as, for example, on a crosslinked polystyrene or other polymer. The phase transfer catalyst is used in an amount of 0.01-2 equivalents on the basis of the amount of Cp compound. In the implementation of the process the components can be added to the reactor in various sequences.

After the reaction is complete, the aqueous phase and the organic phase which contains the Cp compound are separated. When necessary, the Cp compound is recovered from the organic phase by fractional distillation.

The process can be used to obtain mono- and di-, tri-, tetra- and pentasubstituted Cp compounds with the desired cyclic alkyl groups and optionally other groups.

The Cp compounds substituted with one or more cyclic groups according to the invention are particularly suitable for incorporation as a ligand in a metal complex, which, owing to the presence of this ligand, when used as catalyst component, yields a catalyst with an improved activity in comparison with the metal complexes containing the known Cp compounds as a ligand. The invention therefore also relates to a metal complex comprising as ligand at least one cyclopentadiene compound substituted with at least two cyclic alkyl groups.

Further it was found that the presence of at least one substituent on the Cp compound of the form - RDR'_n, where R is a linking group between the Cp and the DR'_n group, D is a hetero atom chosen from group 15 or 16 of the Periodic System of the Elements, R' is a substituent and n is the number of R' groups bound to D, in a substituted Cp compound in which at least one of the other substituents is a cyclic alkyl group and which is used as a ligand in a metal complex, results in a complex which, when used as catalyst component in the polymerization of α-olefins, exhibits better temperature resistance than the presence of a Cp compound substituted only with cyclic groups.

Corresponding complexes in which the Cp compound has not been substituted as described in the foregoing, appear to be unstable or, if they have been stabilized in another way, to yield less active catalysts than the complexes with substituted Cp compounds according to the invention, in particular in the polymerization of α-olefins.

Further it appears that the Cp compounds according to the invention can stabilize highly reactive intermediates such as organometal hydrides, organometal boron hydrides, organometal alkyls and organometal cations. Moreover, they appear to be suitable as stable and volatile precursors for use in Metal Chemical Vapour Deposition. The invention therefore also relates to Cp compounds thus substituted.

From Synthesis, 1993, 684-686, tetramethyl- cyclopentadiene with ethyldimethylamine as fifth substituent is known. This publication does not provide any indication as to the stabilizing effect of the presence of the further substituted Cp compounds according to the invention as ligands in metal complexes. The polysubstituted Cp-compounds according to the invention also comprise a substituent of the form -RDR'_n. The R group constitutes the link between the Cp and the DR'_n group. The length of the shortest link between the Cp and D is critical insofar as it determines, if the Cp compound is used as a ligand in a metal complex, the accessibility of the metal by the DR'_n group so as to obtain the desired intramolecular coordination. If the R group (or bridge) is too short, the DR'_n group may not be able to coordinate properly owing to ring tension.

R is at least one atom long.

The R' groups may each separately be a hydrocarbon radical with 1-20 carbon atoms (such as alkyl, aryl, aralkyl, etc.). Examples of such hydrocarbon radicals are methyl, ethyl, propyl, butyl, hexyl, decyl, phenyl, benzyl and p-tolyl. R' can also be a substituent which, in addition to or instead of carbon and/or hydrogen, comprises one or more hetero atoms from groups 14-16 of the Periodic System of the Elements. Thus a substituent can be a group comprising N, 0 and/or Si. R' should not be a cyclopentadienyl or a group derived therefrom.

The R group can be a hydrocarbon group with 1-20 carbon atoms (such as alkylidene, arylidene, arylalkylidene, etc.). Examples of such groups are methylene, ethylene, propylene, butylene, phenylene, with or without a substituted side chain. The R group preferably has the following structure:

(-ER² ₂-)_p

where p = 1-4 and E represents an atom from group 14 of the Periodic System. The R² groups can each be H or a group as defined for R'.

Thus the main chain of the R group can also comprise silicon or germanium besides carbon. Examples of such R groups are: dialkyl silylene, dialkyl germylene, tetra-alkyl disilylene or dialkyl silaethylene (-(CH₂) (SiR² ₂)-) . The alkyl groups (R²) in such a group preferably have 1 to 4 carbon atoms and are more preferably a methyl or ethyl group. The DR'_π group comprises a hetero atom D chosen from group 15 or 16 of the Periodic System of the Elements and one or more substituents R' bound to D. The number of R' groups (n) is coupled to the nature of the hetero atom D, in the sense that n = 2 if D originates from group 15 and that n = 1 if D originates from group 16. Preferably, the hetero atom D is chosen from the group comprising nitrogen (N) , oxygen (0), phosphorus (P) or sulphur (S); more preferably, the hetero atom is nitrogen (N) . The R' group is also preferably an alkyl, more preferably an n-alkyl group containing 1-20 C atoms. More preferably, the R' group is an n-alkyl containing 1-10 C atoms. Another possibility is that two R' groups in the DR'_n group are joined to each other to form a ring-type structure (so that the DR'_n group may be a pyrrolidinyl group). The DR'_n group may bond coordinatively to a metal.

The Cp compound substituted with at least two cyclic groups and optionally other groups may be substituted with a group of the form RDR'_n, for example via the following synthesis route.

In a first step of this route a substituted Cp compound is deprotonated by reaction with a base, sodium or potassium.

As base can be applied for example organolithium compounds (R³Li) or organomagnesium compounds (R³MgX), where R³ is an alkyl, aryl, or aralkyl group and X is a halide, for example n-butyl lithium or i-propyl-magnesium chloride. Potassium hydride, sodium hydride, inorganic bases, such as NaOH and KOH, and alcoholates of Li, K and Na can also be used as base. Mixtures of the above-mentioned compounds can also be used.

This reaction can be carried out in a polar dispersing agent, for example an ether. Examples of ethers are tetrahydrofuran (THF) or dibutyl ether. Nonpolar solvents, such as for example toluene, can also be used.

Next, in a second step of the synthesis route the cyclopentadienyl anion obtained reacts with a compound of the formula (R'_nD-R-Y) or (X-R-Sul), where D, R, R' and n are as defined in the foregoing. Y is a halogen atom (X) or a sulphonyl group (Sul). The halogen atom X may be for example chlorine, bromine and iodine. The halogen atom X is preferably a chlorine or bromine atom. The sulphonyl group has the form -OS0₂R⁶, wherein R^δ is a hydrocarbon radical containing 1-20 carbon atoms, such as alkyl, aryl, aralkyl. Examples of such hydrocarbon radicals are butane, pentane, hexane, benzene and naphthalene. R⁶ may also contain one or more hetero atoms from groups 14-17 of the Periodic System of the Elements, such as N, 0, Si or F, in addition to or instead of carbon and/or hydrogen. Examples of sulphonyl groups are: phenylmethanesulphonyl , benzenesulphonyl , 1-butanesulphonyl , 2 , 5-dichlorobenzenesulphonyl , 5-dimethylamino-l-naphthalenesulphonyl , pentafluoro- benzenesulphonyl , p-toluenesulphonyl , trichloromethane- sulphonyl, trifluoromethanesulphonyl , 2,4,6- triisopropylbenzenesulphony1 , 2,4,6- trimethylbenzenesulphonyl , 2-mesitylenesulphonyl , methanesulphonyl , 4-methoxybenzenesulphonyl , 1- naphthalenesulphonyl , 2-naphthalenesulphonyl , ethane- sulphonyl, 4-fluorobenzenesulphonyl and 1-hexadecane- sulphonyl. Preferably, the sulphonyl group is p- toluenesulphonyl or trifluoromethanesulphonyl.

If D is a nitrogen atom and Y is a sulphonyl group, the compound according to the formula (R'_nD-R-Y) is formed in situ by reacting an aminoalcohol compound (R'₂NR-0H) with a base (such as described above), potassium or sodium, followed by a reaction with a sulphonyl halide (Sul-X).

The second reaction step can also be carried out in a polar dispersant as described for the first step.

The temperature at which the reaction is carried out is -60 to 80°C. Reactions with X-R-Sul and with DR'_n-R-Y in which Y is Br or I are usually carried out at a temperature between -20 and 20°C. Reactions with DR'_n- R-Y in which Y is Cl are usually carried out at a higher temperature (10 to 80°C). The upper limit for the temperature at which the reactions are carried out is determined in part by the boiling point of the compound R '_nD-R-Y and that of the solvent used.

After the reaction with a compound of the formula (X-R-Sul) another reaction is carried out with LiDR'_n or HDR'_n in order to replace X by a DR'_n functionality. This reaction is carried out at 20 to 80°C, optionally in the same dispersant as mentioned in the foregoing.

During the synthesis process according to the invention, geminal products may in part be formed. A geminal substitution is a substitution in which the number of substituents increases by 1, but in which the number of substituted carbon atoms does not increase. The amount of geminal products formed is low if the synthesis is carried out starting from a substituted Cp compound containing 1 substituent and increases as the substituted Cp compound contains more substituents. If sterically large substituents are present on the substituted Cp compound, geminal products are not, or are scarcely, formed. Examples of sterically large substituents are secondary or tertiary alkyl substituents. The amount of geminal product formed is also low if the second step of the reaction is carried out under the influence of a Lewis base whose conjugated acid has a dissociation constant for which pK_a is less than or equal to -2.5. The pK_a values are based on D. D. Perrin: Dissociation Constants of Organic Bases in Aqueous Solution, International Union of Pure and Applied Chemistry, Butterworths, London 1965. The values have been determined in an aqueous H₂S0₄ solution. Ethers can be mentioned as examples of suitable weak Lewis bases.

If geminal products have formed during the process according to the invention, said products can easily be separated from the non-geminal products by converting the mixture of geminally and non-geminally substituted products into a salt by reaction with potassium, sodium or a base, after which the salt is washed with a dispersant in which the salt of the non- geminal products is insoluble or sparingly soluble. The compounds mentioned above may be used as base. Suitable dispersants are nonpolar dispersants, such as alkanes. Examples of suitable alkanes are: heptane and hexane. Metal complexes comprising as least one cyclopentadiene compound as defined above appear to exhibit improved stability compared with similar complexes in which other Cp compounds are present as ligands. The invention therefore also relates to said metal complexes and to the use thereof as catalyst component for the polymerization of olefins. In these metal complexes one or more Cp compounds according to the invention may be present as ligand. Two of these ligands may be joined by a bridge. Metal complexes which are catalytically active if one of their ligands is a compound according to the invention are complexes of metals from groups 4-10 of the Periodic System and rare earths. In this context, complexes of metals from groups 4 and 5 are preferably used as a catalyst component for polymerizing olefins, complexes of metals from groups 6 and 7 in addition also for metathesis and ring-opening metathesis polymerizations, and complexes of metals from groups 8-10 for oiefin copolymerizations with polar comonomers, hydrogenations and carbonylations. Particularly suitable for the polymerization of olefins are such metal complexes in which the metal is chosen from the group consisting of Ti, Zr , Hf, V and Cr.

The term olefins here and hereinafter refers to α-olefins, diolefins and other ethylenically unsaturated monomers. Where the term 'polymerization of olefins' is used, this refers both to the polymerization of a single type of olefinic monomer and to the copolymerization of two or more olefins.

The synthesis of metal complexes including lanthanide complexes with the above-described specific Cp compounds as a ligand can take place according to the processes known per se for this purpose. The use of these Cp compounds does not require any adaptations of said known processes.

The polymerization of α-olefins, for example ethylene, propylene, butene, hexene, octene and mixtures thereof and combinations with dienes, can be carried out in the presence of the metal complexes with the Cp compounds according to the invention as ligand. Suitable in particular for this purpose are the complexes of transition metals which are not in their highest valency state, in which just one of the cyclopentadienyl compounds according to the invention is present as a ligand and in which the metal is cationic during the polymerization. Said polymerizations can be carried out in the manner known for the purpose and the use of the metal complexes as catalyst component does not make any essential adaptation of these processes necessary. The known polymerizations are carried out in suspension, solution, emulsion, gas phase or as bulk polymerization. The cocatalyst usually applied is an organometal compound, the metal being chosen from Group 1, 2, 12 or 13 of the Periodic System of the Elements. Examples are trialkylaluminium, alkylaluminium halides, alkylaluminooxanes (such as methylaluminoxanes ) , tris(pentafluorophenyl) borate, dimethylanilinium tetra(pentafluorophenyl ) borate or mixtures thereof. The polymerizations are carried out at temperatures between -50°C and +350°C, more particularly between 25 and 250°C. The pressures used are generally between atmospheric pressure and 250 MPa, for bulk polymerizations more particularly between 50 and 250

MPa, and for the other polymerization processes between 0.5 and 25 MPa. As dispersants and solvents, use may be made of, for example, hydrocarbons such as pentane, heptane and mixtures thereof. Aromatic, optionally perfluorinated hydrocarbons, are also suitable. The monomer applied in the polymerization can also be used as dispersant or solvent.

The invention will be elucidated by means of the following examples, without being restricted thereto. For characterization of the products obtained the following analysis methods were used:

Gas chromatography (GC) was performed on a Hewlett Packard 5890 Series II with an HP Crosslinked Methyl Silicon Gum (25 m x 0.32 mm x 1.05 μm) column. Gas chromatography combined with mass spectrometry ( GC- MS ) was performed with a Fisons MD800, equipped with a quadrupole mass detector, autoinjector Fisons AS800 and CPSilβ column (30 m x 0.25 mm x 1 μm , low bleed). NMR was performed with a Bruker ACP200 ( ^lE = 200 MHz? ¹³C = 50 MHz) or Bruker ARX400 NMR ( ^lE = 400 MHz; ¹³C = 100 MHz). Metal complexes were characterized using a Kratos MS80 mass spectrometer or a Finnigan Mat 4610 mass spectrometer .

Experiment I

In-situ preparation of 2-(N,N-dimethylaminoethyl )- tosylate

A solution of n-butyllithium in hexane (1 equivalent) was added at -10°C (dispensing time: 60 minutes) to a solution of 2-dimethylaminoethanol (1 equivalent) in dry THF under dry nitrogen in a three- neck round-bottom flask provided with a magnetic stirrer and a dropping funnel. After all the butyl- lithium had been added, the mixture was brought to room temperature and stirred for 2 hours. The mixture was then cooled (-10°C), after which paratoluenesulphonyl chloride (1 equivalent) was added. The solution was then stirred for 15 minutes at this temperature before it was added to a cyclopentadienyl anion.

Comparable tosylates can be prepared in an analogous way. In a number of the examples below, a tosylate is always coupled to alkylated Cp compounds.

During this coupling, geminal coupling also takes place in addition to the required substitution reaction. In nearly all cases it was possible to separate the geminal isomers from the non-geminal isomers by converting the non-geminal isomers into their sparingly soluble potassium salt, followed by washing of said salt with a solvent in which said salt is not or sparingly soluble. Exampl e I I

Preparation of di (cyclohexyl )cyclopentadiene

A double-walled reactor having a volume of 1 L, provided with baffles, condenser, top stirrer, thermometer and dropping funnel was charged with 600 g of clear 50% strength NaOH (7.5 mol), followed by cooling to 8°C. Then 20 g of Aliquat 336 (49 mmol) and 33 g (0.5 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 172 g of cyclohexylbromide (1.05 mol) was added, cooling with water taking place at the same time. After 2 hours' stirring at room temperature the reaction mixture was heated to 70°C, followed by a further 6 hours' stirring. GC was used to show that at that instant 79% of di (cyclohexyl )cyclopentadiene was present. The product was distilled at 0.04 mbar and 110-120°C. After distillation 73.6 g of di (cyclohexyl ) cyclopentadiene was obtained. Characterization took place with the aid of GC, GC-MS, ¹³C- and Hi-NMR.

b. Preparation of (dimethylaminoethyl )di (cyclohexyl )- cyclopentadiene

A solution of n-butyllithium in hexane (18.7 ml; 1.6 mol/1; 30 mmol) was added dropwise to a cooled (0°C) solution of dicyclohexylcyclopentadiene (6.90 g; 30.0 mmol) in dry tetrahydrofuran (125 ml) under a nitrogen atmosphere in a 250 ml three-neck round-bottom flask provided with magnetic stirrer and dropping funnel. After stirring for 24 hours at room temperature, 2-(dimethylaminoethyl ) tosylate prepared in situ (30.0 mmol) was added. After stirring for 18 hours, the conversion was found to be 88% and water (100 ml) was carefully added dropwise to the reaction mixture, after which the tetrahydrofuran was distilled off. The crude product was extracted with ether, after which the combined organic phase was dried (sodium sulphate) and evaporated down. The residue was purified by means of a column containing silica gel resulting in 7.4 g of (dimethylaminoethyl )dicyclohexyl- cyclopentadiene.

c. Synthesis of l-(dimethylaminoethyl )-2 , 4- dicvclohexylcyclopentadienyltitanium(III) dichloride and f l-(dimethylaminoethyl ) -2 ,4-dicvclohexyl- cvclopentadienyl 1dimethyltitanium(III)

IC_sH₂lc__zC₆H₁₁)_?fCH;,₂NMe_?TiαiI)Me,1 (catalyst IIB,

In a Schlenk vessel, 1.37 g (4.54 mmol) of (dimethylaminoethyl )dicyclohexylcyclopentadiene was dissolved in 30 mL of diethyl ether and the solution was then cooled to -60°C. Then 2.84 mL of n-butyl- lithium (1.6M in hexane; 4.54 mmol) was added dropwise. The reaction mixture was slowly brought to room temperature, followed by stirring for 2 hours. After evaporation of the solvent a yellow powder remained to which 30 mL of petroleum ether was added. In a second Schlenk vessel, 40 mL of tetrahydrofuran was added to 1.68 g of Ti(III)Cl₃.3THF (4.53 mmol). Both Schlenk vessels were cooled to -60°C and the organolithium compound was then added to the Ti(III)Cl₃ suspension. The reaction mixture was then stirred for 18 hours at room temperature, after which the solvent was evaporated. To the residue 50 mL of petroleum ether was added, which was subsequently again evaporated to dryness. A green solid remained containing l-(di- methylaminoethyl )-2 , 4-dicyclohexylcyclopentadienyl- titanium(III) dichloride.

In a Schlenk vessel, 0.31 g (0.671 mmol) of the above-described l-(dimethylaminoethyl)-2 ,4-dicyclo- hexylcyclopentadienyltitanium(III) dichloride was dissolved in 30 mL of diethyl ether. The solution was cooled to -60°C and 0.73 mL (1.84M in diethyl ether; 1.34 mmol) of methyllithium was then added dropwise. The solution was slowly brought to room temperature, followed by stirring for 1 hour. Then the solvent was evaporated and the residue extracted with 40 mL of petroleum ether. The filtrate was boiled down and dried for 18 hours in vacuo. There remained 0.14 g of a black/brown oil containing [ 1-(dimethylaminoethyl )-2 , 4- dicyclohexylcyclopentadienyl ]dimethyltitanium(III) .

Example III a. Preparation of tri (cyclohexyl )cyclopentadiene A double-walled reactor having a volume of 1

L, provided with a baffle, condenser, top stirrer, thermometer and dropping funnel was charged with 600 g of clear 50% strength NaOH (7.5 mol), followed by cooling to 8°C. Then 20 g of Aliquat 336 (49 mmol) and 33 g (0.5 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 256 g of cyclohexyl bromide (1.57 mol) was added, cooling with water taking place at the same time. After 1 hour's stirring at room temperature the reaction mixture was heated to 70°C, followed by a further 2 hours' stirring. After 2 hours, stirring was stopped and phase . separation was awaited. The water layer was drawn off and 600 g (7.5 mol) of fresh 50% strength NaOH were added, followed by a further 4 hours' stirring at 70°C. GC was used to show that at that instant 10% of di- and 90% of tri-(cyclohexyl )- cyclopentadiene were present in the mixture. The product was distilled at 0.04 mbar and 130°C. After distillation, 87.4 g of tri (cyclohexyl)cyclopentadiene was obtained. Characterization took place with the aid of GC, GC-MS, ¹³C- and ^XH-NMR.

b. Preparation of (dimethylaminoethyl )tri (cyclohexyl )- cyclopentadiene The reaction was carried out in a manner identical to that for (dimethylaminoethyl )- dicyclohexylcyclopentadiene. The conversion was 91%. The product was obtained with a yield of 80% via preparative column purification on silica gel using, successively, petroleum ether (40-60°C) and THF as the eluent .

c. Synthesis of l-(dimethylaminoethyl ) -2 , 3 , 5-tri- cyclohexylcyclopentadienyltitanium( IIDdichloride and f 1-(dimethylaminoethyl )-2 , 3 , 5-tricyclohexylcyclo-penta- dienyl 1dimethyltitaniumfIII) rC_sH(c-Hex),(CH₇)₇NMe₇Ti(III)Cl₇1 (catalyst IIIA) and rc₅H(c-Hex)₃fCH_;)₂NMe_?Ti(III)Me,1 (catalyst IIIB)

To lithium (dimethylaminoethyl )- tricyclohexylcyclopentadiene (2.11 g, 5.70 mmol), dissolved in 20 mL of tetrahydrofuran, a cooled slurry (-70°C) of Ti(III)Cl₃.3THF (2.11 g, 5.70 mmol) in 20 mL of THF was added at -70°C. The dark-green solution formed was stirred for 72 hours at room temperature. After this had been boiled down, 30 mL of petroleum ether (40-60) was added. After evaporating to complete dryness once more, a mint-green powder (2.80 g) was obtained, containing l-(dimethylaminoethyl )-2 , 3 , 5- tricyclohexylcyclopentadienyltitanium(III) dichloride. To a slurry, cooled to -70°C, of 0.50 g (0.922 mmol) of the [ l-(dimethylaminoethyl)-2 , 3 ,5-tricyclohexyleyelo- pentadienyltitanium(III)dichloride]•[lithium chloride] obtained above in 30 mL of diethyl ether, 1.15 mL of methyllithium (1.6M in diethyl ether, 1.84 mmol) was added dropwise. The green-brown slurry immediately darkened. Then the mixture was stirred for 1 hour at room temperature, boiled down to complete dryness and dissolved in 40 mL of petroleum ether. After filtration and complete evaporation of the solvent a black powder (0.40 g, 0.87 mmol) was obtained containing tricyclohexyleyelopentadienyl-dimethy1aminoethyl- τi(III)dimethyl. Polymerization experiments IV-VI A. The homopolymerization of ethylene and the copolymerization of ethylene with octene were carried out in the following manner. 600 ml of an alkane mixture

(pentamethylheptane or special boiling point solvent) were introduced as the reaction medium, under dry N₂, into a stainless steel reactor having a volume of 1.5 litres. Then the desired amount of dry octene was introduced into the reactor (this amount can therefore also be zero). The reactor was then, with stirring, heated to the desired temperature under a desired ethylene pressure.

Into a catalyst-dispensing vessel having a volume of 100 ml, 25 ml of the alkane mixture was metered in as solvent. Herein the desired amount of an Al-containing cocatalyst was premixed over a period of 1 minute with the desired quantity of metal complex, such that the ratio Al/(metal in the complex) in the reaction mixture is equal to 2000.

This mixture was then metered into the reactor, upon which the polymerization started. The polymerization reaction thus started was carried out isothermally. The ethylene pressure was kept constant at the set pressure. After the desired reaction time the ethylene supply was stopped and the reaction mixture was drawn off and quenched with methanol.

The reaction mixture containing methanol was washed with water and HCI in order to remove residues of catalyst. Then the mixture was neutralized with

NaHC0₃, after which the organic fraction was admixed with an antioxidant (Irganox 1076, registered trademark) in order to stabilize the polymer. The polymer was dried in vacuo for 24 hours at 70°C. in both cases the following conditions were varied: - metal complex

- type and quantity of cocatalyst

- temperature

The actual conditions are stated in Table I.

TABLE I

10 BF20: tetrakls(pentaphenylborate) MAO: methylaluminoxane from witco

^►

~

O

Claims

C L A I M S

1. Polysubstituted cyclopentadiene compound characterized in that at least two substituents are cyclic alkyl groups, with the exception of di- and tricyclohexylcyclopentadiene and di(-l- methylcyclohexyl)cyclopentadiene.

2. Metal complex comprising as a ligand at least one cyclopentadiene compound substituted with two cyclic alkyl groups.

3. Trisubstituted or polysubstituted cyclopentadiene compound in which at least one substituent is of the form -RDR'_n, where R is a linking group between the cyclopentadiene and the DR'_n group, D is a hetero atom chosen from group 15 or 16 of the Periodic System of the Elements, R' is a substituent and n is the number of R' groups bound to D, and in which at least one of the other substituents is a cyclic alkyl group.

4. Trisubstituted or polysubstituted cyclopentadiene compound according to claim 3, in which R has the structure

(-ER² ₂-)_P where p = 1-4 and E is an atom from group 14 of the Periodic System.

5. Trisubstituted or polysubstituted cyclopentadiene compound according to any one of claims 3-4, in which D is chosen from the group comprising nitrogen (N), oxygen (0), phosphorus (P) or sulphur (S) .

6. Trisubstituted or polysubstituted cyclopentadiene compound according to any one of claims 3-5, in which R' is an N-alkyl group containing 1-20 carbon atoms.

7. Metal complex in which at least one cyclopentadiene compound according to any one of claims 3-6 is present as a ligand.

8. Metal complex according to claim 7, in which the metal is a metal from groups 4-10 of the Periodic System of the Elements and rare earths.

9. Use of the metal complex according to any one of claims 7-8 as a catalyst component for the polymerization of α-olefins.