WO2016170328A1

WO2016170328A1 - Tungsten catalysts

Info

Publication number: WO2016170328A1
Application number: PCT/GB2016/051093
Authority: WO
Inventors: Dermot O'hare; Jean-Charles BUFFET; Christopher Wright
Original assignee: Oxford University Innovation Ltd
Current assignee: Oxford University Innovation Ltd
Priority date: 2015-04-20
Filing date: 2016-04-20
Publication date: 2016-10-27
Anticipated expiration: 2017-10-20
Also published as: GB201506684D0

Abstract

Novel Tungsten-containing compounds of formula I defined herein are disclosed, as well as catalytic compositions comprising the compounds. Also disclosed are uses of the compounds and compositions in alkene oligomerisation reactions.

Description

TUNGSTEN CATALYSTS

INTRODUCTION

[0001 ] The present invention relates to catalysts. More specifically, the present invention relates to particular Tungsten catalysts, and the use of such catalysts in alkene oligomerisation reactions.

BACKGROUND OF THE INVENTION

[0002] Low order alkenes (C2-C3) are readily accessible from the petrochemical industry, by the process of steam cracking, and as such make cheap and readily available feedstock chemicals.

[0003] However, it is higher order alkenes (C4-C12) that hold more commercial worth due to their use in the manufacture of numerous polymers and organic chemicals.

[0004] Therefore the upgrading of cheap and readily available lower order alkenes to higher order alkenes is a desired industrial process.

[0005] The catalytic conversion (upgrading) of low order alkenes to higher order alkenes is well known in the art. Most common are alkene metathesis catalysts, which work by catalysing the redistribution of alkene fragments. However, alkene oligomerisation catalysts are also well known in the art, and are commonly used in industrial conversion of low order alkenes to higher order alkenes. Catalysts known in the art, however, often suffer from either poor stability, selectivity or problems with product separation.

[0006] Thus, there is a need for new alkene oligomerisation catalysts that have improved stability under industrially accepted conditions and/or provide greater ease in separating products. Moreover, due to the high value and importance industry places on pure alkenes, there is a need for new alkene oligomerisation catalysts that have improved selectivity for particular higher order alkenes.

[0007] The present invention was devised with the foregoing in mind.

SUMMARY OF THE INVENTION

[0008] According to a first aspect of the present invention there is provided a compound of the formula I shown below:

(I)

wherein:

W is tungsten;

Q is O, 0->LA or N, wherein LA is a Lewis acid and is a dative bond; bond a is either a single bond or double bond;

bond b is a multiple bond;

Ri , R2 and R₃ are independently selected from halo, (1 -6C)alkyl, aryl(1 - 2C)alkyl or OR_a, wherein R_a is selected from (1 -6C)alkyl, aryl or aryl(1 - 2C)alkyl;

Z is a group selected from (1 -6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃, aryl(1 -2C)alkyl or an aryl optionally substituted by one or more groups selected from (1 -6C)alkyl, (3-6C)cycloalkyl, 3- to 6- membered heterocyclyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, aryl, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, C(0)R_c, C(0)OR_c, OC(0)R_c, C(0)N(R_b)R_c, N(Rb)C(0)R_c, S(0)_yRb (where y is 0, 1 or 2), or (CH₂)zNR_bR_c (where z is 1 or 2), and wherein R_b is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 -6C)alkyl; and

X is an anionic ligand;

with the proviso that:

(i) when Q is 0->LA, Z is absent;

(ii) at least one of Ri , R₂ or R₃ is a group other than halo; and

(iii) when bond a is a double bond one of R₂, R₃ or X is absent;

[0009] According to a second aspect of the present invention, there is provided a catalytic composition comprising a compound of formula I as defined herein and either: (i) a suitable solid support or a suitable activator; or (ii) both a suitable solid support and a suitable activator. [0010] According to a third aspect of the present invention there is provided a use of a compound of formula I as defined herein, or a composition as defined herein, in the oligomerisation of alkenes.

[0011 ] According to a fourth aspect of the present invention there is provided a process of forming alkene oligomers which comprises reacting alkene monomers in the presence of either:

(i) a compound of formula I as defined herein; or

(ii) a catalytic composition as defined herein.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Alkyl

[0012] Unless otherwise specified, the term "alkyl" as used herein includes reference to a straight or branched chain alkyl moieties, typically having 1 , 2, 3, 4, 5 or 6 carbon atoms. This term includes reference to groups such as methyl, ethyl, propyl (n-propyl or isopropyl), butyl (n-butyl, sec-butyl or tert-butyl), pentyl, hexyl and the like. In particular, an alkyl may have 1 , 2, 3 or 4 carbon atoms.

Alkoxy

[0013] Unless otherwise specified, the term "alkoxy" as used herein include reference to -O-alkyl, wherein alkyl is straight or branched chain and comprises 1 , 2, 3, 4, 5 or 6 carbon atoms. In one class of embodiments, alkoxy has 1 , 2, 3 or 4 carbon atoms. This term includes reference to groups such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, pentoxy, hexoxy and the like.

Aryl

[0014] Unless otherwise specified, the term "aryl" as used herein includes reference to an aromatic ring system comprising 6, 7, 8, 9 or 10 ring carbon atoms. Aryl is often phenyl but may be a polycyclic ring system, having two or more rings, at least one of which is aromatic. This term includes reference to groups such as phenyl, naphthyl and the like.

Halogen

[0015] Unless otherwise specified, the term "halogen" or "halo" as used herein includes reference to F, CI, Br or I. In a particular, halogen may be F or CI, of which CI is more common. Cycloalkyl

[0016] Unless otherwise specified, the term "cycloalkyl", "carbocyclyl", "carbocycle" or "carbocyclic" refers to a radical of a non-aromatic cyclic hydrocarbon group, generally having from 3 to 10 ring carbon atoms (i.e. (3-10C)cycloalkyl) and zero heteroatoms in the non-aromatic ring system. Suitably, cycloalkyl groups include (3-nC)cycloalkyl and (3-nC)cycloalkenyl. Exemplary embodiments include: cyclobutyl, cyclobutenyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptenyl, cycloheptadienyl, cycloheptatrienyl, cyclooctyl, cyclooctenyl, bicyclo[2.2.1 ]heptanyl, bicyclo[2.2.2]octanyl, and the like.

Heterocyclyl

[0017] Unless otherwise specified, the term "heterocyclyl", "heterocyclic" or "heterocycle" means a non-aromatic saturated or partially saturated monocyclic, fused, bridged, or spiro bicyclic heterocyclic ring system(s). The term heterocyclyl includes both monovalent species and divalent species. Monocyclic heterocyclic rings contain from about 3 to 12 (suitably from 3 to 6) ring atoms, with from 1 to 5 (suitably 1 , 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur in the ring. Bicyclic heterocycles contain from 7 to 17 member atoms, suitably 7 to 12 member atoms, in the ring. Bicyclic heterocycles contain from about 7 to about 17 ring atoms, suitably from 7 to 12 ring atoms. Bicyclic heterocyclic(s) rings may be fused, spiro, or bridged ring systems. Examples of heterocyclic groups include cyclic ethers such as oxiranyl, oxetanyl, tetrahydrofuranyl, dioxanyl, and substituted cyclic ethers. Heterocycles containing nitrogen include, for example, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, tetrahydrotriazinyl, tetrahydropyrazolyl, and the like. Typical sulfur containing heterocycles include tetrahydrothienyl, dihydro-1 ,3-dithiol, tetrahydro-2H-thiopyran, and hexahydrothiepine. Other heterocycles include dihydro-oxathiolyl, tetrahydro-oxazolyl, tetrahydro-oxadiazolyl, tetrahydrodioxazolyl, tetrahydro-oxathiazolyl, hexahydrotriazinyl, tetrahydro-oxazinyl, morpholinyl, thiomorpholinyl, tetrahydropyrimidinyl, dioxolinyl, octahydrobenzofuranyl, octahydrobenzimidazolyl, and octahydrobenzothiazolyl. For heterocycles containing sulfur, the oxidized sulfur heterocycles containing SO or S02 groups are also included. Examples include the sulfoxide and sulfone forms of tetrahydrothienyl and thiomorpholinyl such as tetrahydrothiene 1 ,1 -dioxide and thiomorpholinyl 1 ,1 -dioxide. A suitable value for a heterocyclyl group which bears 1 or 2 oxo (=0) or thioxo (=S) substituents is, for example, 2-oxopyrrolidinyl, 2-thioxopyrrolidinyl, 2-oxoimidazolidinyl, 2-thioxoimidazolidinyl, 2-oxopiperidinyl, 2,5-dioxopyrrolidinyl, 2,5-dioxoimidazolidinyl or 2,6-dioxopiperidinyl. Particular heterocyclyl groups are saturated monocyclic 3 to 7 membered heterocyclyls containing 1 , 2 or 3 heteroatoms selected from nitrogen, oxygen or sulfur, for example azetidinyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidinyl, morpholinyl, tetrahydrothienyl, tetrahydrothienyl 1 ,1 -dioxide, thiomorpholinyl, thiomorpholinyl 1 ,1 -dioxide, piperidinyl, homopiperidinyl, piperazinyl or homopiperazinyl. As the skilled person would appreciate, any heterocycle may be linked to another group via any suitable atom, such as via a carbon or nitrogen atom. However, reference herein to piperidino or morpholino refers to a piperidin-1 -yl or morpholin-4-yl ring that is linked via the ring nitrogen.

Substitued

[0018] Unless otherwise specified, the term "substituted" as used herein in reference to a moiety means that one or more, especially up to 5, more especially 1 , 2 or 3, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of the described substituents. The term "optionally substituted" as used herein means substituted or unsubstituted.

[0019] It will, of course, be understood that substituents are only at positions where they are chemically possible, the person skilled in the art being able to decide (either experimentally or theoretically) without inappropriate effort whether a particular substitution is possible. For example, amino or hydroxy groups with free hydrogen may be unstable if bound to carbon atoms with unsaturated (e.g. olefinic) bonds. Additionally, it will of course be understood that the substituents described herein may themselves be substituted by any substituent, subject to the aforementioned restriction to appropriate substitutions as recognised by the skilled person.

[0020] Unless otherwise specified, the term "optionally substituted" refers to either groups, structures, or molecules that are substituted and those that are not substituted. The term "wherein a/any CH, CH₂, CH₃ group or heteroatom (i.e. NH) within a R¹ group is optionally substituted" suitably means that (any) one of the hydrogen radicals of the R¹ group is substituted by a relevant stipulated group.

[0021 ] Where optional substituents are chosen from "one or more" groups it is to be understood that this definition includes all substituents being chosen from one of the specified groups or the substituents being chosen from two or more of the specified groups.

[0022] The phrase "compound of the invention" means those compounds which are disclosed herein, both generically and specifically. Amounts

[0023] Where the quantity or concentration of a particular component of a given composition is specified as a weight percentage (wt% or %w/w), said weight percentage refers to the percentage of said component by weight relative to the total weight of the composition as a whole. It will be understood by those skilled in the art that the sum of weight percentages of all components of a composition will total 100 wt%. However, where not all components are listed (e.g. where compositions are said to "comprise" one or more particular components), the weight percentage balance may optionally be made up to 100 wt% by unspecified ingredients (e.g. a diluent, such as water, or other nonessential^ but suitable additives).

Lewis Acid

[0024] Unless otherwise specified, the term "Lewis acid" refers to a substance that can accept a pair of non-bonding electrons. In other words, a Lewis acid can be defined as an electron-pair acceptor. Lewis acids can include atoms, ions and molecules which are capable of accepting a pair of electrons. A non-exhaustive list of Lewis acids include: Cu²⁺, Fe²⁺, Fe³⁺, BF₃, BCI₃, AICI₃, AIBr₃, SiX₄, FeCI₃, FeBr₃ and SnCU.

Dative bond

[0025] Unless otherwise specified, the term "dative bond" refers to a covalent bond formed between two atoms where both electrons come from the same atom. It is sometimes referred to as a coordinate bond.

β- Hydrogen

[0026] Unless otherwise specified, the term "β-hydrogen" refers to a hydrogen atom directly bonded to a β-carbon. The β carbon refers to the second carbon attached to a functional group.

Catalytic compounds

[0027] As described hereinbefore, the present invention provides a compound of the formula I shown below:

(I)

wherein:

W is tungsten;

bond b is a multiple bond;

Z is a group selected from (1 -6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃, aryl(1 -2C)alkyl or an aryl optionally substituted by one or more groups selected from (1 -6C)alkyl, (3-6C)cycloalkyl, 3- to 6- membered heterocycle, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, aryl, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, C(0)R_c, C(0)OR_c, OC(0)R_c, C(0)N(R_b)R_c, N(Rb)C(0)R_c, S(0)_yRb (where y is 0, 1 or 2), or (CH₂)zNR_bR_c (where z is 1 or 2), and wherein R_b is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 -6C)alkyl; and

X is an anionic ligand;

with the proviso that:

(i) when Q is 0->LA, Z is absent;

(ii) at least one of Ri , R₂ or R₃ is a group other than halo; and

(iii) when bond a is a double bond one of R₂, R₃ or X is absent.

[0028] The compounds of the invention may be used as effective alkene oligomerisation catalysts. In particular, the compounds of the present invention may display superior catalytic performance when compared to current alkene oligomerisation catalysts, due to either an improved selectivity, an improved stability or an improved turnover, or combinations therefore.

[0029] A person skilled in the art will understand that bond b may comprise a number of different bond types (e.g. single bond, double bond, triple bond and/or dative bond). Suitably, bond b is selected from a single bond with a dative component, a double bond with a dative component or a double bond, such that bond b takes one of the following forms:

wherein J is a coordinate (dative) bond .

[0030] Particular compounds of the invention include, for example, compounds of the formula (I), wherein, unless otherwise stated, each of Ri , R₂, R3, bond a, bond b, Q, X, Z and any associated substituent group has any of the meanings defined hereinbefore or in any of paragraphs (1 ) to (40) hereinafter:- (1 ) Ri , R₂ and R₃ are independently selected from (1 -6C)alkyl, aryl(1 -2C)alkyl or OR_a, wherein R_a is selected from (1 -6C)alkyl, aryl or aryl(1 -2C)alkyl;

(2) Ri , R₂ and R₃ are independently selected from (1 -6C)alkyl, aryl(1 -2C)alkyl or OR_a, wherein R_a is selected from (1 -6C)alkyl;

(3) Ri , R₂ and R₃ are independently selected from (1 -6C)alkyl, aryl(1 -2C)alkyl or OR_a, wherein R_a is selected from (1 -6C)alkyl, provided that said (1 -6C)alkyl, aryl(1 - 2C)alkyl or OR_a group contains no β-hydrogens.

(4) Ri , R₂ and R₃ are independently selected from (1 -6C)alkyl or aryl(1 -2C)alkyl, provided that said (1 -6C)alkyl or aryl(1 -2C)alkyl group contains no β-hydrogens. (5) Ri , R₂ and R₃ are independently selected from methyl, benzyl or a group of the formula:

wherein R_d is selected from a (1 -2C)alkyl;

Ri , R₂ and R₃ are independently selected from methyl or a group of the formula:

wherein R_d is selected from a (1 -2C)alkyl;

(7) Ri , R₂ and R₃ are methyl;

(8) bond a is a single bond;

(9) bond a is a double bond;

(10) bond b is a single bond with a dative component, a double bond or a double bond with a dative component;

(1 1 ) bond b is a double bond or a double bond with a dative component;

(12) bond b is a double bond;

(13) Q is N or O;

(14) Q is C→LA or N, wherein LA is a BF₃, BCI₃, AICI₃, AIBr₃,SiX₄, FeCI₃, FeBr₃ or SnCU and is a dative bond;

(15) Q is 0->LA or N, wherein LA is a AICI₃ or BF₃ and is a dative bond;

(16) Q is N;

(17) X is selected from halo, OAc, hydride, phosphonate, sulphonate, borate, cyclopentadienyl, pentamethylcyclopentadienyl, or pentamethylindenyl or indenyl;

(18) X is selected from halo, OAc, hydride, cyclopentadienyl, pentamethylcyclopentadienyl, indenyl or pentamethylindenyl;

(19) X is selected from halo, OAc, hydride, phosphonate, sulphonate, borate, or (1 - 4C)alkoxy;

(20) X is selected from halo, OAc or hydride;

(21 ) X is selected is CI, Br or I;

(22) X is CI;

(23) Z is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, aryl(1 -2C)alkyl or an aryl, wherein said aryl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, 3- to 6-membered heterocycyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,ORb, NR_bR_c, aryl, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, C(0)R_c, C(0)OR_c, OC(0)R_c, C(0)N(Rb)R_c, N(Rb)C(0)R_c, S(0)_yR_b (where y is 0, 1 or 2), or (CH₂)zNR_bR_c (where z is 1 or 2), and wherein R_b is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 -6C)alkyl; (24) Z is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, benzyl or an aryl, wherein said aryl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, 3- to 6-membered heterocycyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,ORb, NR_bR_c, aryl, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, and wherein R_b is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 -6C)alkyl;

(25) Z is selected from (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, 3- to 6-membered heterocycyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,ORb, NR_bR_c, aryl, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, and wherein R_b is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 -6C)alkyl;

(26) Z is selected from (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, and wherein R_b and R_c are independently selected from H or (1 - 6C)alkyl;

(27) Z is selected from (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃,OR_b, NR_bR_c, halo, amino, cyano, nitro, and wherein R_b and R_c are independently selected from H or (1 -4C)alkyl;

(28) Z is selected from (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2-4C)alkyl, SiMe₃ or OMe;

(29) Z is an aryl substituted by one or more groups selected from (2-6C)alkyl, (3- 6C)cycloalkyl, 3- to 6-membered heterocycyl, Si[(1 -4C)alkyl]₃, Si[0(1 - 4C)alkyl)]₃,OR_b, NR_bR_c, aryl, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, C(0)R_c, C(0)OR_c, OC(0)R_c, C(0)N(R_b)R_c, N(R_b)C(0)R_c, S(0)_yR_b (where y is 0, 1 or 2), or (CH₂)_zNR_bR_c (where z is 1 or 2), and wherein R_b is selected from (1 -6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 -6C)alkyl;

(30) Z is a phenyl substituted by one or more groups selected from (2-6C)alkyl, (3- 6C)cycloalkyl, 3- to 6-membered heterocycyl, Si[(1 -4C)alkyl]₃, Si[0(1 - 4C)alkyl)]₃,OR_b, NR_bR_c, aryl, halo or amino, wherein R_b is selected from (1 - 6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 - 6C)alkyl;

(31 ) Z is a phenyl substituted by one or more groups selected from (2-6C)alkyl, (3- 6C)cycloalkyl, 3- to 6-membered heterocycyl, Si[(1 -4C)alkyl]₃, Si[0(1 - 4C)alkyl)]₃,ORb, NR_bR_c, aryl, halo or amino, wherein R_b is selected from (1 - 6C)alkyl, (3-6C)cycloalkyl, aryl or aryl(1 -2C)alkyl and R_c is selected from H or (1 - 6C)alkyl;

(32) Z is a phenyl substituted by one or more groups selected from (2-6C)alkyl, (3- 6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, aryl, halo or amino, wherein R_b and R_c are independently selected from H or (1 -6C)alkyl;

(33) Z is (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a group of the formula:

wherein;

R_e and Rf are independently selected from hydrogen, (2-6C)alkyl, (3- 6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_h, NR_hRi, aryl, halo or amino, wherein R_h and R, are independently selected from H or (1 -6C)alkyl; and

R_g is selected from hydrogen, (1 -4C)alkyl or (1 -4C)alkoxy;

(34) Z is (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a group of the formula:

wherein;

R_e and Rf are independently selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_h, NRhRi, aryl, halo or amino, wherein R_h and Ri are independently selected from H or (1 -6C)alkyl; and R_g is selected from hydrogen, (1 -4C)alkyl or (1 -4C)alkoxy;

(35) Z is (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a group of the formula:

wherein;

R_e and Rf are independently selected from (2-6C)alkyl, ORh Or NR_hRi, wherein R_h and R, are independently selected from H or (1 -6C)alkyl; and

R_g is selected from hydrogen, (1 -4C)alkyl or (1 -2C)alkoxy;

(36) Z is (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a group of the formula:

wherein;

R_e and R_f are independently selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_h, NRhRi, aryl, halo or amino, wherein R_h and Ri are independently selected from H or (1 -6C)alkyl;

Z is a group of the formula:

wherein;

R_e and R_f are independently selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_h, NRhRi, aryl, halo or amino, wherein R_h and Ri are independently selected from H or (1 -6C)alkyl; (38) Z is a group of the formula:

wherein;

R_e and Rf are independently selected from (2-6C)alkyl, (Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,ORh or NR_hRi, wherein R_h and R, are independently selected from H or (1 -6C)alkyl;

Z is a group of the formula:

wherein;

R_e and Rf are independently selected from (2-6C)alkyl, ORh or NR_hR, wherein R_h and R, are independently selected from H or (1 -6C)alkyl;

(40) Z is 2,6-diisopropylphenyl.

(41 ) Z is phenyl substituted with 1 , 2 or 3 substituents selected from methyl, methoxy, halo and trifluoromethyl.

(42) Z is phenyl substituted with 1 or 3 methyl substituents, or 1 , 2 or 3 substituents selected from halo, methoxy and trifluoromethyl.

(43) Z is selected from :

(44) Z is selected from :

(45) Z is selected from:

[0031 ] In one embodiment, the compounds of the invention are the compounds of formula (I) wherein:

Ri , R₂ and R₃ are as defined in any one of paragraphs (5) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in any one of paragraphs (10) to (12);

Q is as defined in any one of paragraphs (13) to (16);

Z is as defined in any one of paragraphs (33) to (40); and

X is as defined in any one of paragraphs (20) to (22).

[0032] In a particular group of compounds of the invention, R₃ is methyl, i.e. the compounds have the structural formula la (a sub-definition of formula (I)) shown below:

(la)

wherein Z, Q, Ri , R₂, X, bond a and bond b each have any one of the meanings defined herein.

[0033] In one embodiment of the compounds of formula la:

Ri and R₂ are as defined in any one of paragraphs (1 ) to (7); bond a is as defined in any one of paragraphs (8) to (9); bond b is as defined in any one of paragraphs (10) to (12) Q is as defined in any one of paragraphs (13) to (16);

Z is as defined in any one of paragraphs (23) to (40); and X is as defined in any one of paragraphs (17) to (22).

[0034] In another embodiment of the compounds of formula la:

Ri and R₂ are as defined in any one of paragraphs (1 ) to (7); bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in any one of paragraphs (17) to (22).

[0035] In another embodiment of the compounds of formula la:

Ri and R₂ are as defined in any one of paragraphs (5) to (7); bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (25) to (40); and

X is as defined in any one of paragraphs (17) to (22).

[0036] In another embodiment of the compounds of formula la:

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (33) to (40); and

X is as defined in any one of paragraphs (21 ) to (22).

[0037] In another embodiment of the compounds of formula la:

Ri and R₂ are as defined in any one of paragraphs (6) to (7); bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (39) to (40); and

X is as defined in any one of paragraphs (21 ) to (22). [0038] In a particular group of compounds of the invention, R₂ and R₃ are methyl, i.e. the compounds have the structural formula lb (a sub-definition of formula (I)) shown below:

(lb)

wherein Z, Q, Ri , X, bond a and bond b each have any one of the meanings defined herein.

[0039] In one embodiment of the compounds of formula lb:

Ri is as defined in any one of paragraphs (1 ) to (7);

bond a is as defined in any one of paragraphs (8) to (9);

bond b is as defined in any one of paragraphs (10) to (12);

Q is as defined in any one of paragraphs (13) to (16);

Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in any one of paragraphs (17) to (22).

[0040] In another embodiment of the compounds of formula lb:

Ri is as defined in any one of paragraphs (1 ) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in any one of paragraphs (17) to (22).

[0041 ] In another embodiment of the compounds of formula lb:

Ri is as defined in any one of paragraphs (5) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in any one of paragraphs (17) to (22). [0042] In another embodiment of the compounds of formula lb:

Ri is as defined in any one of paragraphs (5) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (33) to (40); and

X is as defined in any one of paragraphs (21 ) to (22).

[0043] In another embodiment of the compounds of formula lb:

Ri is as defined in any one of paragraphs (6) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

Z is as defined in any one of paragraphs (39) to (40); and

X is as defined in any one of paragraphs (21 ) to (22).

[0044] In a particular group of compounds of the invention, Q is N, Ri, R₂ and R₃ are methyl and bond a is a single bond, i.e. the compounds have the structural formula Ic (a sub-definition of formula (I)) shown below:

(IC)

wherein Z, bond b and X each have any one of the meanings defined herein.

[0045] In one embodiment of the compounds of formula Ic:

bond b is as defined in any one of paragraphs (10) to (12);

Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in any one of paragraphs (17) to (22).

[0046] In another embodiment of the compounds of formula Ic:

bond b is as defined in paragraph (12);

Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in any one of paragraphs (19) to (22).

[0047] In another embodiment of the compounds of formula Ic:

bond b is as defined in paragraph (12); Z is as defined in any one of paragraphs (23) to (40); and

X is as defined in paragraph (22).

[0048] In another embodiment of the compounds of formula lc:

bond b is as defined in paragraph (12);

Z is as defined in any one of paragraphs (24) to (40); and

X is as defined in any one of paragraphs (17) to (22).

[0049] In another embodiment of the compounds of formula lc:

bond b is as defined in paragraph (12);

Z is as defined in any one of paragraphs (24) to (28); and

X is as defined in any one of paragraphs (16) to (21 ).

[0050] In another embodiment of the compounds of formula lc:

bond b is as defined in paragraph (12);

Z is as defined in any one of paragraphs (33) to (40); and

X is as defined in any one of paragraphs (16) to (21 ).

[0051 ] In another embodiment of the compounds of formula lc:

bond b is as defined in paragraph (12);

Z is as defined in any one of paragraphs (39) to (40); and

X is as defined in any one of paragraphs (16) to (21 ).

[0052] In another embodiment of the compounds of formula lc:

bond b is as defined in paragraph (12);

Z is as defined in any one of paragraphs (39) to (40); and

X is as defined in paragraph (21 ).

[0053] In a particular group of compounds of the invention, Q is N, Ri , R₂ and R₃ are methyl, bond a is a single bond and Z is as shown below, i.e. the compounds have the structural formula Id (a sub-definition of formula (I)) shown below:

wherein R_e, Rf, R_g, bond b and X each have any one of the meanings defined herein.

[0054] In one embodiment of the compounds of formula Id:

bond b is as defined in any one of paragraphs (10) to (1 2);

R_e and Rf are as defined in paragraph (33);

R_g is as defined in any one of paragraphs (33) to (35); and

X is as defined in any one of paragraphs (17) to (22).

[0055] In another embodiment of the compounds of formula Id:

bond b is as defined in paragraph (12) ;

R_e and Rf are as defined in paragraph (30);

R_g is as defined in any one of paragraphs (33) to (35); and

X is as defined in any one of paragraphs (21 ) to (22).

[0056] In another embodiment of the compounds of formula Id:

bond b is as defined in paragraph (12) ;

R_e and Rf are as defined in paragraph (30);

R_g is as defined in any one of paragraphs (33) to (35); and

X is as defined in paragraph (22).

[0057] In another embodiment of the compounds of formula Id:

bond b is as defined in paragraph (12) ;

R_e and Rf are as defined in paragraph (30);

R_g is as defined in paragraph (35); and

X is as defined in paragraph (22).

[0058] In a particular group of compounds of the invention, Q is N, Ri , R₂ and R₃ are methyl, bond a is a single bond, bond b is a double bond and Z is as shown below, i.e. the compounds have the structural formula le (a sub-definition of formula (I)) shown below:

(le)

wherein R_e, Rt and X each have any one of the meanings defined herein.

[0059] In one embodiment of the compounds of formula le:

R_e and Rf are as defined in any one of paragraphs (36) to (39); and

X is as defined in any one of paragraphs (17) to (22).

[0060] In one embodiment of the compounds of formula le:

R_e and Rf are as defined in any one of paragraphs (36) to (39); and

X is as defined in any one of paragraphs (21 ) to (22).

[0061 ] In one embodiment of the compounds of formula le:

R_e and Rf are as defined in any one of paragraphs (38) to (39); and

X is as defined in any one of paragraphs (21 ) to (22).

[0062] In a particular group of compounds of the invention, Z is as shown below, i.e. the compounds have the structural formula If (a sub-definition of formula (I)) shown below:

wherein Ri , R₂, R3, bond a, bond b, Q, X, R_e, Rf and R_g have any one of the meanings defined herein.

[0063] In one embodiment of the compounds of formula If:

Ri , R2 and R₃ are as defined in any one of paragraphs (1 ) to (7);

bond a is as defined in any one of paragraphs (8) to (9);

bond b is as defined in any one of paragraph (10) to (12);

Q is as defined in any one of paragraphs (13) to (16);

R_e and Rf are as defined in paragraph (33);

R_g is as defined in any one of paragraphs (33) to (35); and

X is as defined in any one of paragraphs (17) to (22).

[0064] In another embodiment of the compounds of formula If:

Ri , R2 and R₃ are as defined in any one of paragraphs (1 ) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

R_e and Rf are as defined in paragraph (33);

R_g is as defined in any one of paragraphs (33) to (35); and

X is as defined in any one of paragraphs (17) to (22).

[0065] In another embodiment of the compounds of formula If:

Ri , R2 and R₃ are as defined in any one of paragraphs (5) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

R_e and Rf are as defined in paragraph (33);

R_g is as defined in any one of paragraphs (33) to (35); and

X is as defined in any one of paragraphs (20) to (22).

[0066] In another embodiment of the compounds of formula If:

Ri , R2 and R₃ are as defined in any one of paragraphs (6) to (7);

bond a is as defined in paragraph (8);

bond b is as defined in paragraph (12);

Q is as defined in paragraph (16);

R_e and Rf are as defined in paragraph (33);

R_g is as defined in paragraph (35); and

X is as defined in any one of paragraphs (21 ) to (22). [0067] Particular compounds of the present invention include any of the compounds exemplified in the present application, and, in particular, the following compound:

[0068] In another embodiment, the compound of formula (I) has a structure according to any of the following:

[0069] The compounds of the present invention may additionally be limited by one or both of the following provisos:

(i) when Q is N, Ri , R₂ or R₃ are methyl, bond b is a double bond and X is fluorine, Z is not methyl, phenyl or 2,6-dimethylphenyl; or

(ii) when Q is N, Ri , R₂ or R₃ are methyl, bond b is a double bond and X is either chlorine, OC(CH₃)3 or cyclopentadienyl, Z is not phenyl.

[0070] Therefore it will be understood that the compounds of formula I, as defined in any one of paragraphs (1 ) to (40) above, or a structure according to any one of formulae (la) to (If) may be limited by the above provisos. Suitably, the compounds according to any one of formulae (la) to (le) may be limited by the above provisos. [0071 ] Certain compounds of the present invention comprising ethyl moieties at the Ri , R₂ and R₃ positions may have a lower affinity than other compounds, perhaps owing to the presence of β-hydrogens. Therefore in another embodiment of the invention Ri , R₂ and R₃ are not ethyl.

[0072] In one embodiment, tungsten is in oxidation state (VI).

[0073] The compounds of the present invention may be converted into another catalytically active species during their use in catalytic applications. A person skilled in the art will appreciate that the compounds administered in the catalytic process may themselves be the active catalytic species or may be converted into another active catalytic species during the course of the reaction. The person skilled in the art would also appreciate the likely forms of the active species in such catalytic reactions. A non- limiting example of such conversion would be where W(NAr)Me3CI, wherein Ar is 2,6- diisopropylphenyl, is converted into W(NAr)CH₂Me₂ or W(NAr)CH₂MeCI (shown below) during the course of the reaction.

It will be understood that any of the above structures may also include an additional bond from N to W of dative character.

[0074] The compounds of this invention may possess one or more asymmetric centres; such compounds can therefore be produced as individual (R)- or (S)-stereoisomers or as mixtures thereof. Unless indicated otherwise, the description or naming of a particular compound in the specification and claims is intended to include both individual enantiomers and mixtures, racemic or otherwise, thereof. The methods for the determination of stereochemistry and the separation of stereoisomers are well-known in the art (see discussion in Chapter 4 of "Advanced Organic Chemistry", 4th edition J. March, John Wiley and Sons, New York, 2001 ), for example by synthesis from optically active starting materials or by resolution of a racemic form. It is to be understood that the present invention encompasses all optical, diastereoisomers and geometric isomers and mixtures thereof that possess catalytic activity.

[0075] The present invention also encompasses compounds of the invention as defined herein which comprise one or more isotopic substitutions. For example, H may be in any isotopic form, including 1 H, 2H(D), and 3H (T); C may be in any isotopic form, including 12C, 13C, and 14C; and O may be in any isotopic form, including 160 and 180; and the like.

[0076] It is also to be understood that certain compounds of the formula (I) may exist in solvated as well as unsolvated forms such as, for example, hydrated forms. It is to be understood that the invention encompasses all such solvated forms that possess catalytic activity.

Catalytic compositions

[0077] As defined hereinbefore, the present invention provides a catalytic composition comprising a compound of formula I as defined herein and either: (i) a suitable solid support or a suitable activator; or (ii) both a suitable solid support and a suitable activator.

[0078] Suitably, when envisaged for use in the oligomerisation of alkene monomers, the compounds of the invention are immobilized on a suitable solid support as defined herein. The compounds of the invention may be immobilized directly on the solid support, or via a suitable linker. The compounds of the invention may be immobilized on the solid support by one or more ionic or covalent interactions. Immobilizing the compounds of the present invention on a suitable solid support may result in superior performance in the oligomerisation of alkenes. In particular, the immobilizing the compounds of the present invention on a suitable solid support may improve product separation and catalyst recovery.

[0079] Suitably, the compound of formula I is immobilized on the solid support. The compound of the invention may be immobilized directly on the solid support, or via a suitable linker.

[0080] In an embodiment, the compound of the invention is immobilized on the solid support by one or more ionic or covalent interactions.

[0081 ] In an embodiment, the solid support may also be an activator. [0082] It is to be understood that a suitable activator is something that helps mediate, initiate or enhance the catalytic reaction. The term "activator" may be used synonymously with the term "co-catalyst".

[0083] Suitable activators are well known in the art and include, but are not limited to, aluminium derivatives (e.g. trimethylaluminium (TMA), dimethyl aluminiumchloride (DMAC), methylaluminiumdichloride (AIMeCI₂), methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) and triethylaluminium (TEA)).

[0084] In a particular embodiment, the suitable activator is selected from trimethylaluminium (TMA), methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA). Suitably, the suitable activator is methylaluminoxane (MAO).

[0085] Suitable solid supports are also well known in the art and include, but are not limited to, silica, silica-MAO, polymethylaluminoxane (also known as 'solid MAO'), a layered double hydroxide (LDH), LDH-MAO, aqueous miscible organic layered double hydroxides (AMO-LDHs), zirconia and titania.

[0086] In an embodiment, the solid support is selected from silica-MAO, polymethylaluminoxane (also known as 'solid MAO'), a layered double hydroxide (LDH), LDH-MAO. It will be understood that silica-MAO denotes MAO activated silica, and LDH- MAO denotes MAO activated layered double hydroxide.

[0087] It is understood that a person skilled in the art will understand the meaning of the term "a layered double hydroxide". In one embodiment, the layered double hydroxide of the suitable solid support is of the formula:

{[M^z+(i-_x) M'y⁺ _x(OH)₂]^a+ (Xⁿ )a/n^»bH₂0^»c(AMO-solvent)}_q (I) wherein,

M^ and M^,y± are two (or more) different charged metal cations;

z = 1 or 2;

y = 3 or 4;

0 < x < 0.9;

b is 0 to 10;

c is 0.0 to 10, preferably c > 0.01 and < 10,

q > 0;

X^n_ is an anion with n > 0, preferably 1 -5

a = z(1 -x) + xy-2; and

the AMO-solvent is an aqueous miscible organic solvent. [0088] In another embodiment, the layered double hydroxide of the suitable solid support is of the formula {[Mg(i-x)Alx(OH)₂]^a+

(wherein X is selected from C0₃, N0₃ or S0₄).

[0089] In a particular embodiment, the solid support is provided as an activator. Suitably, the activated support is insoluble under the polymerisation conditions. Suitable activated supports include methylaluminoxane activated silica (Si0₂), solid methylaluminoxane and methylaluminoxane activated AMO-MgAI-X layered double hydroxide (eg {[Mg₍i-x)Alx(OH)₂]^a+

(0.1 < x > 0.9; X = anion eg. C0₃ ^2", OH^", P, C , Br, , S0₄ ^2", N0₃ ^" and P0₄ ^3"), b is a number less than 1 , b is 0 or a number greater than 0 which gives compounds optionally hydrated with a stoichiometric amount or a non-stoichiometric amount of water and/or an aqueous- miscible organic solvent (AMO-solvent), such as acetone.

[0090] In another embodiment, the solid support is Solid MAO. Solid methyl aluminoxane (MAO) (often referred to as polymethylaluminoxane) is distinguished from other methyl aluminoxanes (MAOs) as it is insoluble in hydrocarbon solvents and so acts as a heterogeneous support system. Any suitable solid MAO support may be used.

[0091 ] In contrast to non-solid (hydrocarbon-soluble) methyl aluminoxanes, which are traditionally used as an activator species in slurry polymerisation or to modify the surface of a separate solid support material (e.g. Si0₂), solid MAO is itself suitable for use as a support material, without the need for an additional activator.

[0092] In an embodiment, the solid MAO is prepared by heating a solution containing polymethylaluminoxane and a hydrocarbon solvent (e.g. toluene), so as to precipitate solid MAO. The solution containing polymethylaluminoxane and a hydrocarbon solvent may be prepared by reacting trimethyl aluminium and benzoic acid in a hydrocarbon solvent (e.g. toluene), and then heating the resulting mixture.

[0093] In an embodiment, the solid polymethylaluminoxane is prepared according to the following protocol:

Benzoic acid

inoxane

AIMe₃ MAO Solid MAO

r

The properties of the solid polymethylaluminoxane can be adjusted by altering one or more of the processing variables used during its synthesis. For example, in the above- outlined protocol, the properties of the solid polymethylaluminoxane may be adjusted by varying the Al:0 ratio, by fixing the amount of AIMe₃ and varying the amount of benzoic acid. Exemplary Al:0 ratios are 1 :1 , 1 .1 :1 , 1 .2:1 , 1 .3:1 , 1 .4:1 and 1 .6:1 . Suitably the Al:0 ratio is 1 .2:1 or 1 .3:1 . Alternatively, the properties of the solid polymethylaluminoxane may be adjusted by fixing the amount of benzoic acid and varying the amount of AIMe₃.

[0094] In another embodiment, the solid polymethylaluminoxane is prepared according to the following protocol:

_{MMe »} Aluminoxane 1.. ^ MAO ·*_* Solid MAO

0.5 h precursor _{2¾ h 1 h}

15 C ^{+ CH}* 0 ¾

[0095] In the above protocol, steps 1 and 2 may be kept constant, with step 2 being varied. The temperature of step 2 may be 70-100°C (e.g. 70°C, 80°C, 90°C or 100°C). The duration of step 2 may be from 12 to 28 hours (e.g. 12, 20 or 28 hours). The duration of step 2 may be from 5 minutes to 24 hours. Step 3 may be conducted in a solvent such as toluene.

[0096] In an embodiment, the aluminium content of the solid polymethylaluminoxane falls within the range of 36-41 wt%.

[0097] In an embodiment, the solid MAO support is insoluble in benzene, toluene and hexane. The solid polymethylaluminoxane useful as part of the present invention is characterised by extremely low solubility in toluene and n-hexane. In an embodiment, the solubility in n-hexane at 25°C of the solid polymethylaluminoxane is 0-2 mol%. Suitably, the solubility in n-hexane at 25°C of the solid polymethylaluminoxane is 0-1 mol%. More suitably, the solubility in n-hexane at 25 °C of the solid polymethylaluminoxane is 0-0.2 mol%. Alternatively or additionally, the solubility in toluene at 25°C of the solid polymethylaluminoxane is 0-2 mol%. Suitably, the solubility in toluene at 25°C of the solid polymethylaluminoxane is 0-1 mol%. More suitably, the solubility in toluene at 25°C of the solid polymethylaluminoxane is 0-0.5 mol%. The solubility in solvents can be measured by the method described in JP-B(KOKOKU)-H07 42301 . [0098] In another embodiment, the solid MAO support is in particulate form. Suitably, the particles of the solid MAO support are spherical, or substantially spherical, in shape.

[0099] In a particularly suitable embodiment, the solid MAO support is as described in US2013/0059990, WO2010/055652 or WO2013/146337 and obtainable from Tosoh Finechem Corporation, Japan.

[00100] In a preferred embodiment, the composition comprises solid MAO as the suitable solid support, wherein the solid support functions as an activator, and, optionally, another activator selected from methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA).

[00101] It will be understood that for the compositions of the invention, the compounds of the invention may be associated with the solid support by any suitable means. For example, the compounds of the invention may be bonded to the solid support via one or more ionic or covalent interactions. The reaction scheme below provides a schematic illustration of how W(NDipp)Me₃CI (derived from W(NDipp)CI₄(THF)) may be associated with solid MAO.

Synthesis

[00102] The compounds of the present invention can be prepared by any suitable technique known in the art. Particular processes for the preparation of these compounds are described further in the accompanying examples.

[00103] In the description of the synthetic methods described herein and in any referenced synthetic methods that are used to prepare the starting materials, it is to be understood that all proposed reaction conditions, including choice of solvent, reaction atmosphere, reaction temperature, duration of the experiment and workup procedures, can be selected by a person skilled in the art. [00104] It is understood by one skilled in the art of organic/inorganic synthesis that the functionality present on various portions of the molecule must be compatible with the reagents and reaction conditions utilised.

[00105] Generally, the processes of preparing a compound of the present invention as defined herein comprises:

reacting a compound of formula A:

Formula A

(wherein W, Q, X, bond b and Z are each as defined hereinbefore and LG is a suitable leaving group, such as halo, OAc and the like.)

with one or more of the compounds of the formula B:

M(R)₃

Formula B

(wherein M is a suitable metal (e.g. aluminum) and R is selected from Ri , R₂ or R₃ which are as defined hereinbefore).

[00106] In an embodiment, the compound of formula A is provided as a solvate. In particular, the compound of formula A may be provided as an ether (e.g. Et₂0) solvate.

[00107] Any suitable solvent may be used in the synthesis defined above. A particularly suitable solvent is toluene, benzene or THF. A most suitable solvent is benzene.

[00108] A person of skill in the art will be able to select suitable reaction conditions (e.g. temperature, pressures, reaction times, agitation etc.) for such a synthesis.

[00109] Compounds of formula A can be readily synthesized by techniques well known in the art. A person of skill in the art will be able to select suitable reaction conditions (e.g. temperature, pressures, reaction times, agitation etc.) for such a synthesis. Applications

[00110] In another aspect, the present invention provides the use of compounds of formula (I) as defined herein, or a catalytic composition as defined herein, as an alkene oligomerisation catalyst.

[00111] It will be understood that compounds of formula (I) used may be as defined in any one of paragraphs (1 ) to (40), or (1 ) to (45), above, or may have a structure according to any one of formulae (la) to (If).

[00112] Similarly, it will be understood the catalytic compositions used may be any of the catalytic compositions defined herein.

[00113] It will be understood that any of the embodiments discussed below may be applicable to both the compounds of the invention and the catalytic compositions of the invention.

[00114] As discussed hereinabove, the compounds of the invention may be used as effective alkene oligomerisation catalysts. In particular, the compounds of the present invention may display superior catalytic performance when compared to current alkene oligomerisation catalysts, due to either an improved selectivity, an improved stability or an improved turnover, or combinations therefore.

[00115] It will be understood that the term "oligomerisation" used herein is distinct from polymerisation. Oligomers are commonly understood to be molecules containing only a few repeat units, in contrast to polymers, wherein the number of monomeric repeat units is not limited. Dimers, trimers and tetramers are therefore understood to be oligomers.

[00116] In an embodiment, the compounds of formula (I) as defined herein, or catalytic compositions as defined herein, are used as oligomerisation catalysts for the preparation of oligomers comprising 2-10 repeat monomeric units. Suitably, the compounds of formula (I) as defined herein, or catalytic compositions as defined herein, are used as oligomerisation catalysts for the preparation of oligomers comprising 2-6 repeat monomeric units. More suitably, the compounds of formula (I) as defined herein, or catalytic compositions as defined herein, are used as oligomerisation catalysts for the preparation of dimers.

[00117] In one embodiment, the compounds of the present invention , may be used as an alkene oligomerisation catalyst for the production of alkene oligomers. More specifically, the compounds of the present invention can be used as an alkene oligomerisation catalyst for the selective production of butenes, in particular 1 -butene. [00118] In one embodiment, the compounds of the present invention can be used as alkene dimerisation catalyst.

[00119] In another embodiment, the compounds of the present invention can be used to catalyse the oligomerisation of alkene monomers comprising 2 or more carbons. Suitably, the compounds and compositions of the present invention can be used to catalyse the oligomerisation of ethene monomers.

[00120] Accordingly, the compounds of the present invention may be used in the oligomerisation of alkenes. Suitably, the compounds of the present invention may be used in the oligomiersation of alkene monomers. More suitably, the compounds of the present invention may be used in the dimerisation of alkene monomers. Even more suitably, the compounds of the present invention may be used in the dimerisation of alkene monomers comprising 2 or more carbons.

[00121] The present invention also provides a process of forming alkene oligomers which comprises reacting alkene monomers in the presence of either:

(i) a compound of formula I as defined herein; or

(ii) a catalytic composition as defined herein.

[00122] It will be understood that the process may employ compounds of formula (I) as defined in any one of paragraphs (1 ) to (40), or (1 ) to (45), above, or having a structure according to any one of formulae (la) to (If).

[00123] Similarly, it will be understood that the process may employ a catalytic compositions as defined herein. Accordingly, the catalytic composition comprises a compound of formula I as defined herein and either: (i) a suitable solid support or a suitable activator; or (ii) both a suitable solid support and a suitable activator.

[00124] It will be understood that in the process of the invention, the alkene oligomers are prepared by a process of oligomerisation. Hence, the alkene monomers are oligomerised to higher order alkene oligomers (e.g. ethene is oligomerised to butene).

[00125] In one embodiment, the mole ratio of suitable activator to compound of formula (I) is 1 :1 to 1 :30. Suitably, the ratio is 1 :1 to 1 :10. More suitably, the ratio is 1 :1 to 1 :5. Most suitably the ratio is 1 :1 to 1 :2.

[00126] In another embodiment, the process for forming an alkene oligomer proceeds at a temperature of between 0 and 200 °C. Suitably, the process for forming an alkene oligomer proceeds at a temperature of between 0 and 150 °C. More suitably, the process for forming an alkene oligomer proceeds at a temperature of between 0 and 100 °C. Most suitably, the process for forming an alkene oligomer proceeds at a temperature of between 20 and 100 °C.

[00127] In another embodiment, the process for forming an alkene oligomer proceeds at a temperature of between 40 and 120 °C. Suitably, the process for forming an alkene oligomer proceeds at a temperature of between 40 and 80 °C. More suitably, the process for forming an alkene oligomer proceeds at a temperature of between 40 and 60 °C.

[00128] In another embodiment, the process for forming an alkene oligomer is performed for a period of 0.5 to 24 hours. Suitably, the process for forming an alkene oligomer is performed for a period of 5 to 24 hours.

[00129] In another embodiment, the process for forming an alkene oligomer proceeds at a pressure of between 1 and 100 bar. Suitably, the process for forming an alkene oligomer proceeds at a pressure of between 1 and 50 bar. More suitably, the process for forming an alkene oligomer proceeds at a pressure of between 10 and 50 bar.

[00130] In another embodiment, the process for forming an alkene oligomer proceeds via slurry oligomerisation, wherein the compounds of the present invention are supported on a suitable solid support.

[00131] In another embodiment, the process for forming an alkene oligomer proceeds via a fixed bed reaction, wherein gaseous alkene monomer is passed over the compound of the present invention to produce an alkene oligomer.

[00132] In another embodiment, the alkene monomers are ethylene monomers.

[00133] In a preferred embodiment, the composition used in the process comprises solid MAO as the suitable solid support, wherein the solid support functions as an activator, and, optionally, another activator selected from methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA).

[00134] The following numbered paragraphs describe particular aspects and embodiments of the invention:

(1 ) A compound of the formula I shown below:

(I)

wherein:

W is tungsten;

bond b is a multiple bond;

X is an anionic ligand;

with the proviso that:

(i) when Q is 0->LA, Z is absent;

(ii) at least one of Ri , R₂ or R₃ is a group other than halo; and

(iii) when bond a is a double bond one of R₂, R₃ or X is absent.

(2) A compound according to paragraph 1 , wherein Q is N.

(3) A compound according to paragraph 1 or 2, wherein bond a is a single bond.

(4) A compound according to paragraph 1 or 2, wherein bond a is a double bond. (5) A compound according to paragraphs 1 to 4, wherein bond b is a double bond.

(6) A compound according to paragraphs 1 to 5, wherein Ri , R₂ and R₃ are

independently selected from methyl or a group of the formula:

wherein R_d, is selected from a (1 -2C)alkyl.

(7) A compound accordingly to paragraphs 1 to 6, wherein one of Ri , R₂ or R₃ is methyl, with the proviso that:

(ii) when Q is N, Ri , R₂ or R₃ are methyl, bond b is a double bond and X is either chlorine, OC(CH₃)₃ or cyclopentadienyl, Z is not phenyl.

(8) A compound according to paragraphs 1 to 7, wherein Ri , R₂ and R₃ are methyl.

(9) A compound according to any one of the preceding paragraphs, wherein X is selected from halo, OAc, hydride, phosphonate, sulphonate, borate,

cyclopentadienyl, pentamethylcyclopentadienyl, indenyl, pentamethylindenyl or (1 -4C)alkoxy.

(10) A compound according to any one of the preceding paragraphs, wherein X is CI.

(1 1 ) A compound according to any one of the preceding paragraphs, wherein Z is selected from (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, and wherein R_b and R_c are independently selected from H or (1 - 6C)alkyl.

(12) A compound according to any one of the preceding paragraphs, wherein Z is phenyl substituted by one or more groups selected from (2-6C)alkyl, (3- 6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, aryl, halo or amino, wherein R_b and R_c are independently selected from H or (1 -6C)alkyl. (13) A compound according to any one of the preceding paragraphs, wherein Z is a group of the formula:

wherein;

R_g and Rh are independently selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,ORi, NR,Rj, aryl, halo or amino, wherein Ri and Rj are independently selected from H or (1 -6C)alkyl.

(14) A compound according to any one of the preceding paragraphs, wherein Z is 2,6-diisopropylphenyl.

(15) A compound of the formula:

(16) A catalytic composition comprising a compound of formula I as defined in any one of paragraph s1 to 15, and either: (i) a suitable solid support or a suitable activator; or (ii) both a suitable solid support and a suitable activator.

(17) The catalytic composition of paragraph 16, wherein the suitable solid support is also an activator.

(18) The catalytic composition of any one of paragraphs 16 to 17, wherein the suitable solid support is selected from silica, silica-MAO, polymethylalumioxane, a layered double hydroxide, LDH-MAO, aqueous miscible organic layered double hydroxides (AMO-LDHs), zirconia or titania.

(19) The catalytic composition according to any one of paragraphs 16 to 18, wherein the suitable activator is selected from trimethylaluminium (TMA), methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA).

(20) The catalytic composition according to any one of paragraphs 16 to 18, wherein the suitable solid support is polymethylaluminoxane, and the composition, optionally, comprises a suitable activator selected from trimethylaluminium (TMA), methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA).

(21 ) The use of a compound of formula I as defined in any one of paragraphs 1 to 15, or a catalytic composition as defined in paragraphs 16 to 20, in the oligomerisation of alkene monomers.

(22) The use according to paragraph 20, wherein the compound of formula I, or the composition as defined in paragraphs 16 to 20, catalyses the

oligomerisation of alkenes comprising two or more carbons.

(23) The use according to paragraphs 21 and 22, wherein the oligomerisation is dimerisation.

(24) The use according to any one of paragraphs 21 . 22 or 23, wherein the alkene monomers are ethylene and the oligomer formed is butene.

(25) The use according to paragraph 24, wherein the alkene monomers are ethylene and the oligomer formed is 1 -butene.

(26) A process of forming alkene oligomers which comprises reacting alkene monomers in the presence of either:

(i) a compound of formula I as defined in any one of paragraphs 1 to 15; or

(ii) a composition as defined in paragraphs 16 to 20.

(27) A process according to paragraph 26, wherein the alkene oligomers are formed by the dimerisation of alkene monomers.

(28) A process according to paragraph 26 or 27, wherein the alkene

monomers comprise two or more carbon atoms.

(29) A process according to any one of paragraphs 26 to 28, wherein the

catalytic composition comprises a ratio of compound of formula I to activator of between 1 :1 and 1 :30.

(30) A process according any one of paragraphs 26 to 29, wherein the

activator of the catalytic composition comprises an aluminium derivative.

(31 ) A process according to paragraph 30, wherein the aluminium derivative is selected from trimethylaluminium (TMA), dimethyl aluminiumchloride (DMAC), methylaluminiumdichloride (AIMeC^), methylaluminoxane (MAO),

polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA).

(32) A process according to paragraph 30 or 31 , wherein the aluminium

derivative is methylaluminoxane (MAO) or polymethylaluminoxane.

(33) A process according to any one of paragraphs 26 to 32, wherein the

suitable solid support of the catalytic composition is also an activator.

(34) A process according to any one of paragraphs 26 to 33, wherein the

suitable solid support of the catalytic composition is selected from silica, silica- MAO, polymethylalumioxane, a layered double hydroxide, LDH-MAO, aqueous miscible organic layered double hydroxides (AMO-LDHs), zirconia or titania.

(35) A process according any one of paragraphs 26 to 34, wherein the suitable solid support is polymethylaluminoxane.

EXAMPLES

[00135] Examples of the invention will now be described by reference to the accompanying figures, in which:

Figure 1 shows the conversion of ethylene to 1 - and 2-butenes for varying additive ratios.

Figure 2 shows the conversion of ethylene to 1 - and 2-butenes for varying additive ratios, including 1 :2 ratio.

Figure 3 shows 1 -butene conversion with variation of additive ratio.

Figure 4 shows the products formed over time from the 1 :5 ratio of compound of formula I: additive.

Figure 5 shows the percentage conversion of ethylene for varying additive ratios.

Figure 6 shows the percentage of ethylene and products vs time for the 1 :5 ratio of compound of formula I: additive.

Figure 7 shows the low field region of a ¹ H NMR spectrum showing the products formed from the reaction of W(NAr)Me₃CI with MAO (W:AI = 1 :5) and ethylene (1 bar) at 100 °C after 148.5 h, wherein Ar is 2,6-diisopropylphenyl.

Figure 8 shows the high field region of a ¹ H NMR spectrum showing the products formed from the reaction of W(NAr)Me₃CI with MAO (W:AI = 1 :5) and ethylene (1 bar) at 100 °C after 148.5 h, wherein Ar is 2,6-diisopropylphenyl. Figure 9 shows the high field regions for ¹ H NMR spectra of W(NAr)Cl4(Et₂0) supported on MgAIC0₃, showing the formation of 1 -butene (1 .92 and 0.89 ppm), 2-butenes (1 .57 (trans) and 1 .5 (cis) ppm), propylene (1 .54 ppm) and methane (0.16 ppm) in C₆D₆ at 100 °C from ethylene (1 bar), wherein Ar is 2,6-diisopropylphenyl.

Figure 10 shows the high field regions for ¹ H NMR spectra of W(NAr)CI₄(Et₂0) supported on Si0₂, showing the formation of 1 -butene (1 .92 and 0.89 ppm), 2-butenes (1 .57 (trans) and 1 .5 (cis) ppm), propylene (1 .54 ppm) and methane (0.16 ppm) in C₆D₆ at 100 °C from ethylene (1 bar), wherein Ar is 2,6-diisopropylphenyl.

Figure 1 1 shows the high field regions for ¹ H NMR spectra of W(NAr)Cl4(Et20) supported on polyaluminoxane, showing the formation of 1 -butene (1 .92 and 0.89 ppm), 2-butenes (1 .57 (trans) and 1 .5 (cis) ppm), propylene (1 .54 ppm) and methane (0.16 ppm) in C₆D₆ at 100 °C from ethylene (1 bar), wherein Ar is 2,6-diisopropylphenyl.

Figure 12 shows the high field regions for ¹ H NMR spectra of W(NAr)CI₄(Et₂0) supported on MgAIS0₄, showing the formation of 1 -butene (1 .92 and 0.89 ppm), 2-butenes (1 .57 (trans) and 1 .5 (cis) ppm), propylene (1 .54 ppm) and methane (0.16 ppm) in C₆D₆ at 100 °C from ethylene (1 bar), wherein Ar is 2,6-diisopropylphenyl.

Figure 13 shows the ¹³C{¹ H} NMR spectrum of W(NDipp)CI₄(Et₂0) in C₆D₆.

Figure 14 shows the ¹³C CPMAS solid state NMR spectrum of Mg₃AIN0₃-W(NDipp)CI₄.

Figure 15 shows the ²⁷AI NMR spectrum of Mg₃AIN0₃-W(NDipp)CI₄.

Figure 16 shows the ¹³C CPMAS solid state NMR spectrum of Si0₂-W(NDipp)CI₄(THF).

Figure 17 shows the ¹³C CPMAS solid state NMR spectrum of Mg₃AIS0₄- W(NDipp)CI₄(THF).

Figure 18 shows the ²⁷AI solid state NMR spectrum of Mg₃AIS0₄-W(NDipp)CI₄(THF).

Figure 19 shows the ¹³C{¹ H} NMR spectrum of W(NDipp)Me₃CI in C₆D₆. Resonance at 1 .38 ppm corresponds to silicone grease.

Figure 20 shows the ¹³C CPMAS solid state NMR spectrum of the complex formed when W(NDipp)CI (THF) is supported on polymethylaluminoxane.

Figure 21 shows the ²⁷AI solid state NMR spectrum of the complex formed when W(NDipp)CI (THF) is supported on polymethylaluminoxane.

Figure 22 shows the ¹³C CPMAS solid state NMR of the complex formed when W(NDipp)CI₄(THF) is supported of Mg₃AIS0₄-MAO. Figure 23 shows the ²⁷AI solid state NMR spectrum of the complex formed when W(NDipp)CI₄(THF) is supported on Mg₃AIS0₄-MAO.

Figure 24 shows the ¹³C CPMAS solid state NMR spectrum of W(NDipp)CL₄ contacted with MAO (W:AI = 1 :2) prior to immobilisation on Mg₃AIS0₄.

Figure 25 shows the ²⁷AI solid state NMR spectrum of W(NDipp)CL₄ contacted with MAO (W:AI = 1 :2) prior to immobilisation on Mg₃AIS0₄.

Figure 26 shows the ¹³C CPMAS solid state NMR spectrum of Mg₃AIS0₄- W(NDipp)Me₃CI.

Figure 27 shows the ²⁷AI solid state NMR spectrum of Mg₃AIS0₄-W(NDipp)Me₃CI.

Figure 28 shows the molecular structure of W(NMes)CI (THF).

Figure 29 shows the Ή NMR spectrum of W(NMes)CI₄(THF) in C₆D₆.

Figure 30 shows the ¹ H NMR spectrum of W(NMes)Me₃CI in C₆D₆, formed from the reaction of W(NMes)CI₄(THF) and excess trimethylaluminium (-0.3 ppm).

Figure 31 shows the molecular structure of W(N(2,6-xylyl))CI₄(THF).

Figure 32 shows the¹ H NMR spectrum of W(N(2,6-xylyl))CI₄(THF) in C₆D₆.

Figure 33 shows the molecular structure of W(N(2,6-xylyl))Me₃CI.

Figure 34 shows the ¹ H NMR spectrum of W(N(2,6-xylyl))Me₃CI in C₆D₆.

Figure 35 shows the molecular structure of W(NPh)CI (THF).

Figure 36 shows the ¹ H NMR spectrum of W(NPh)CI₄(THF) in C₆D₆.

Figure 37 shows the¹ H NMR spectrum of W(NPh)Me₃CI in C₆D₆.

Figure 38 shows the molecular structure of W(N(C₆H₃F₂)CI₄(THF).

Figure 39 shows the ¹ H NMR spectrum of W(N(C₆H₃F₂)CI₄(THF) in C₆D₆.

Figure 40 shows the ¹ H NMR spectrum of W(N(C₆H₃F₂))Me₃CI in C₆D₆

Figure 41 shows the molecular structure of W(N(C₆H₄OMe)CI₄(THF).

Figure 42 shows the Ή NMR spectrum of W(N(C₆H₄OMe)CI₄(THF) in C₆D₆.

Figure 43 shows the molecular structure of W(N(C₆H₄OMe)Me₃CI.

Figure 44 shows the Ή NMR spectrum of W(N(C₆H₄OMe)Me₃CI in C₆D₆.

Figure 45 shows the molecular structure of W(N(C₆H₃(CF₃)₂))CI₄(THF). Figure 46 shows the ¹ H NMR spectrum of W(N(C₆H3(CF3)2))Me₃CI in C₆D₆.Resonance at 0.29 ppm corresponds to silicone grease.

Figure 47 shows the turnover numbers for the reaction of W(N(C6H₃OMe))Me3CI and ethylene 1 bar in C₆D₆ at 100, 75 and 50 °C.

Figure 48 shows a comparison of the poymethylaluminoxane supported W(NDipp)CI₄(THF) with the silica and LDH supported complexes and the most active homogeneous W:AI mole ratio (1 :2) at 100 °C in C₆D₆ and 1 bar ethylene.

Figure 49 shows the oligomerisation activity of the different W(imido)CU(THF) complexes supported on polymethylaluminoxane in C₆D₆ at 100 °C and 1 bar ethylene.

Figure 50 shows the oligomerisation activity of the polymethylaluminoxane supported W(N(C₆H₃OMe))CI₄(THF) complex at 100, 75 and 50 °C in C₆D₆ and 1 bar ethylene.

Figure 51 shows the turnover number (TON) over time for the varying W:MAO ratios. [W(NDipp)Me₃CI] = 4.55 μηιοΙ.

Figure 52 shows the percentage selectivity for 1 -butene over time for the varying W:MAO ratios. [W(NDipp)Me₃CI] = 4.55 μηιοΙ.

Experimental details

General details

[00136] All manipulations were performed in a MBraun Unilab glove box or using standard Schlenk techniques under an inert N₂ atmosphere. Reaction solvents (benzene, toluene, hexane) were dried using an MBraun SPS 800 solvent purification system and stored on either 3 A molecular sieves (benzene) or potassium mirror (toluene, hexane) in pre-dried glass Rotaflo or Young's tap ampoules. Anhydrous pyridine (Sigma Aldrich) was stored on 3 A molecular sieves in a pre-dried glass Rotaflo ampoule. Ethylene was dried over a column containing 3 A molecular sieves. C₆D₆ (Sigma Aldrich) was dried over NaK, vacuum transferred and freeze-pump-thaw degassed prior to use. C₄D₈0 was dried over calcium hydride, filtered and stored over 3 A molecular sieves.

Solution phase NMR spectroscopy

[00137] NMR spectra were measured on a 400 MHz Bruker Avance III HD NanoBay spectrometer. ¹ H and ¹³C{¹ H} NMR spectra were recorded at 25 °C and referenced internally to the residual protio-solvent resonance of the deuterated solvent used. ¹ H and ¹³C{¹ H} chemical shifts, δ, are given in parts per million (ppm).

Solid state NMR spectroscopy

[00138] Samples were prepared in the glovebox and packed in 4 mm Zr0₂ rotors. Solid state ¹³C and ²⁷AI NMR spectra were recorded on a Bruker AVIII HD NanoBay 400 MHz Solid-State NMR spectrometer. Samples were spun at the magic angle (54.71 °) at a spin rate of 10 kHz (¹³C CPMAS) or 15 kHz (²⁷AI DPMAS). ¹³C NMR spectra were referenced to adamantane and ²⁷ Al to AI(N0₃)₃.

Gas chromatography mass spectrometry (GC-MS)

[00139] GC-MS were recorded on an Agilent Technologies 7820A GC system equipped with a PLOT column (27.5 m x 0.32 mm x 5 μηι), coupled to an Agilent Technologies 5977E MSD instrument

Experimental Procedures and Syntheses

Synthesis of WfNArjMe^CI {wherein Ar is 2,6-diisopropylphenyl)

[00140] The starting complex W(NAr)Cl4(Et₂0) was synthesised according to a literature procedure reported by Schrock et al. {Organometallics 1990, 9, 2262-2275).

[00141 ] W(NAr)CI₄(Et₂0) (500 mg, 0.87 mmol) and trimethylaluminium (TMA) (62.7 mg, 0.87 mmol) were charged in separate Schlenks in the glovebox. Benzene (-20 ml) was added to both and the TMA solution transferred across with stirring. This led to an immediate colour change of the tungsten complex from green to dark orange/brown. The solvent was reduced in vacuo and the resulting brown solid dissolved in hexane to yield an orange solution. This was filtered, reduced to minimum volume and placed in the -30 °C freezer, resulting in orange crystals (300 mg) that were suitable for single crystal X- ray diffraction and shown to be W(NAr)Me₃CI. Yield 78.6%.

[00142] ¹ H NMR (C₆D₆) δ (ppm): 7.04 (d, 2H, ArH_meta), 6.97 (dd, 1 H, ArH_para) , 3.53 (sept, 2H, ArCH(CH₃)₂), 1 .41 (s, 9H, W(CH₃)₃, ²JWH = 7.027 Hz), 1 .08 (d, 12H, ArCH(CH₃)₂).

[00143] ¹³C{¹ H} NMR (C₆D₆) δ (ppm): 150.42 (Αη_ρ30Ν), 127.94 (Ar_metaH), 123.22 (Ar_ParaH) , 56.54 (W(CH₃)₃) , 28.83 (ArCH(CH₃)₂), 24.28 (ArCH(CH₃)₂). Quaternary ArCH(CH₃)₂ unobserved. [00144] Complex also shown to form in reactions with MAO and dimethylaluminium chloride (DMAC) in place of TMA.

Solid supported catalysts

Catalyst supports

[00145] W(NAr)CI₄(Et₂0) and W(NAr)Me₃CI have been supported on layered double hydroxides (LDHs) of the type MgAIX where X = C0₃, N0₃ and S0₄ prepared by the aqueous miscible organic solvent treatment method or so called AMO-LDHs, LDH-MAO, polymethylaluminoxane ('solid MAO'), silica and silica-MAO.

General supporting procedure

[00146] 5% W(NAr)CI₄(Et₂0) by weight is reacted with the chosen support. In the case of polymethylaluminoxane, W(NAr)Cl4(Et₂0) (10 mg, 17.4 μηιοΙ), and polymethylaluminoxane (200 mg) were charged in separate Schlenks. Toluene (-20 ml) was added to both and the green complex solution filtered across. The resulting suspension was swirled intermittently for one hour. Immediate decolouration of the green solution was observed and the colourless support became yellow. After one hour the solution was completely clear and colourless at which point it was filtered off. The remaining solid was washed with pentane (2 x 20 ml) and dried in vacuo to yield a yellow solid in near quantitative yield.

[00147] The yellow colouration of the solid suggests formation of the trimethyl complex on the surface which has been confirmed by solution NMR in ds-THF.

[00148] A variety of polymethylaluminoxane supports can be used in this synthesis. An exemplary solid MAO is prepared by an adaptation of the optimised procedure in Kaji et al. in the US 8,404,880 B2 embodiment 1 (Scheme 1 ). For brevity, each synthesised solid MAO is represented as solid MAO(Step 1 Al:0 ratio/Step 2 temperature in ^time in h/Step 3 temperature in °C,time in h). Hence, the synthesis conditions outlined in Scheme 1 would yield solid MAO(1 .2/70,32/100,12). STEP 1

PhCO_?H

2.4 AIMe₃ Aluminoxane pMAO ** solid MAO precursor

15 ^f€ 1 ΠΟ "O

+ MeH

0.5 h

Scheme 1 - Synthesis of solid MAO (1 .2/70,32/100,12)

[00149] A Rotaflo ampoule containing a solution of trimethyl aluminium (2.139 g, 2.967 mmol) in toluene (8 mL) was cooled to 15 °C with rapid stirring, and benzoic acid (1 .509 g, 1 .239 mmol) was added under a flush of N₂ over a period of 30 min. Effervescence (presumably methane gas, MeH) was observed and the reaction mixture appeared as a white suspension, which was allowed to warm to room temperature. After 30 min the mixture appeared as a colourless solution and was heated in an oil bath at 70 °C for 32 h (a stir rate of 500 rpm was used). The mixture obtained was a colourless solution free of gelatinous material, which was subsequently heated at 100 °C for 12 h. The reaction mixture was cooled to room temperature and hexane (40 mL) added, resulting in the precipitation of a white solid which was isolated by filtration, washed with hexane (2 x 40 mL) and dried in vacuo for 3 h. Total yield = 1 .399 g (71 % based on 40 wt% Al).

Ethylene oligomerisation

General oligomerisation procedure

[00150] An internal standard stock solution was made by adding pyridine (10 μΙ_, 124 μηιοΙ) to C₆D₆ (240 μΙ_) using a microlitre syringe. 20 μΙ_ of stock solution (9.93 μηιοΙ pyridine) was added to each NMR tube prior addition of ethylene. For supported complexes where the support was not either composed of MAO or the surface hadn't been contacted with MAO prior to supporting, MAO (2 mg, W:AI = 1 :40) was added prior to starting the run. Runs were periodically analysed by ¹ H NMR spectroscopy and once stopped by GCMS.

Homogeneous oligomerisation

[00151] W(NAr)Me₃CI (2 mg, 4.55 μηιοΙ) and MAO (1 .3 mg, W:AI = 1 :5) were added to a Young's tap NMR tube and dissolved in C₆D₆ (500 mg). The internal standard was added and the solution freeze-pump-thaw degassed three times. Ethylene (1 bar) was added and the tube heated at 100 °C. Formation of 1 -butene was observed by ¹ H NMR spectroscopy along with some isomerisation to 2-butenes and a small amount of propylene as the metathesis product. It should be noted that a small amount of methane was also observed.

Supported oligomerisation

[00152] The supported complex (5 mg) was added to a Young's tap NMR tube, along with MAO if required, and dissolved in C₆D₆ (500 mg). The internal standard was added and the tube freeze-pump-thaw degassed three times. Ethylene (1 bar) was added and the run started.

Results

Homo eneous oli omerisation

[00153] The W(NAr)Me₃CI:additive (MAO) ratio was varied, with the following ratios used: 1 :2, 1 :5, 1 :10 and 1 :20. The homogeneous oligomerisation was carried out as detailed above.

[00154] The results of the homogeneous oligomerisation of ethylene are summarised in Tables 1 to 8 and Figures 1 to 6 and 51 to 52.

Table 1 - the conversion of ethylene to 1- and 2-butenes for varying complex: MAO ratios at 100 V and 1 bar ethylene pressure.

the conversion of ethylene to 1- and 2-butenes for varying complex:MAO ratios at 100 V and 1 bar ethylene pressure.

Table 3 - the ercentage conversion of ethylene to butenes for varying activator ratios.

Table 5 - turnover number (TON) for the varying W:MAO ratios over time

Table 6 - showing the percentage of ethylene and products vs time for the 1:5 ratio.

Table 7 - the ratio of products formed (1-butene, cis-2-butene and trans-2-butene) with varying cocatalyst ratios by ¹H NMR spectroscopy and GCMS analysis.

Table 8 - 1-butene selectivity for the varying W:MAO ratios

Supported oligomerisation

[00155] W(NAr)CI₄(Et20) was supported on polymethylaluminoxane (thus forming the proposed W(NAr)Me₃CI) and the oligomerisation was carried out as described above.

[00156] The results of the supported oligomerisation of ethylene are summarised in Table 9 and Figures 9 to 12.

Table 9 - the ratio of products (1-butene, cis-2-butene and trans-2-butene) from the reaction of W(NAr)CI₄(Et₂0) supported on polyaluminoxane with ethylene at 75, 50 and

25 °C by ¹H NMR spectroscopy and GCMS analysis.

[00157] Of note is the fact that the isomerisation of 1 -butene formed from the dimerisation of ethylene is greatly reduced when the catalyst is supported compared to the homogeneous reaction.

Characterisation studies

[00158] Figures 13 to 18 show the complex W(NDipp)CI₄(Et₂0) (wherein 'Dipp' denotes 2,6-diisopropylphenyl) supported on the surface of Layered Double Hydroxides and silica resulting in the proposed species W(NDipp)CI₃ being bound to surface oxygen atoms. In the ¹³C NMR spectral resonances in the region 120-160 ppm correspond to aromatic carbon environments and 10-30 the isopropyl groups. ²⁷AI spectral resonances for LDHs show the bulk aluminium environment (~ 8 ppm) along with the surface aluminium sites (^« 77 ppm).

[00159] Figures 19 to 27 collectively show that when W(NDipp)CI₄(Et₂0) is supported on a methylaluminium-containing support material (e.g. polymethylaluminoxane or LDH- MAO), the W(NDipp)CU(Et20) species undergoes reaction with the methylaluminium species, resulting in the postulated formation of the corresponding trimethyl complex (e.g. W(NDipp)Me₃CI) on the surface of the support material. In the ¹³C NMR spectra, resonances in the region 120-160 ppm correspond to aromatic carbon environments and 10-30 the isopropyl groups. Resonances around 45 ppm correspond to methyl groups bound to tungsten.

Further oligomerisation studies

Catalytic compounds studied

[00160] Figures 28 to 46 show the tungsten imido complexes synthesised during this study, including molecular structures and ¹ H NMR spectroscopy. Another compound used in this study is W(NDipp)CU(THF) (wherein 'Dipp' denotes 2,6-diisopropylphenyl).

[00161] The general synthetic method used to prepare these compounds is as follows: The relevant isocyanate RNCO is reacted with W(0)CU in octane at reflux for 16 hours. The compounds (e.g. W(NR)CU) can be recrystallized from THF or Et₂0 as the adduct (e.g. W(NR)CI₄(THF)).

The adduct (e.g. W(NR)CI₄(THF)) is converted into the corresponding W(NR)Me₃CI complex according to the following procedure (provided in respect of the preparation of W(NDipp)Me₃CI wherein Dipp = 2,6^JPr-C₆H₃): W(NDipp)CI₄(Et₂0) (500 mg, 0.87 mmol) and trimethylaluminium (TMA) (62.7 mg, 0.87 mmol) were dissolved in benzene (-20 mL) and the TMA solution added dropwise to the green W(NDipp)CU(Et20) solution. This led to an immediate colour to dark orange/brown. The solvent was reduced in vacuo and the resulting brown solid dissolved in hexane to yield an orange solution. This was filtered, reduced to minimum volume and cooled to -30 °C, resulting in orange crystals (300 mg) that were suitable for a single crystal X-ray diffraction study and shown to be W(NDipp)Me₃CI.

[00162] Selected tungsten imido compounds used in this study were supported on solid support materials selected from silica, layered double hydroxide and polymethylaluminoxane (solid MAO). The general synthetic method used to prepare these supported compounds is as follows:

Layered Double Hydroxides (LDHs) of the type Mg₃AIX where [Mg₀.75Alo.25(OH)₂](X"^~)o.25/n (X = C0₃, NO3 and S0₄) were prepared by the aqueous miscible organic solvent treatment method (AMOST),^2"4 and were thermally treated at 150 °C for 6 h under vacuum prior to use. LDH-MAO was prepared by reacting 2 equivalents of LDH to one equivalent of MAO in toluene at 80 °C for 2 hours. The resulting suspension was filtered and dried to yield a white solid. Polymethylaluminoxane was synthesised as described hereinbefore.

5% W(NDipp)CI₄(Et₂0) by weight was reacted with the chosen support in toluene. For example W(NDipp)CI₄(Et₂0) (10 mg, 17.4 μηιοΙ), and Mg₃AIS0₄ (200 mg) were charged in separate schlenks. Toluene (-20 ml) was added to both and the green complex solution filtered across. The resulting suspension was swirled intermittently for one hour. Immediate decolouration of the green solution was observed and the colourless support became orange. After one hour the solution was completely clear and colourless at which point it was filtered off. The remaining solid was washed with pentane (2 x 20 mL) and dried in vacuo to yield a beige solid in near quantitative yield. The colour of the support varied dependent on the solid used; both silica and Mg₃AIC0₃ yielded beige powders, whereas Mg₃AIS0₄ was off-white, Mg₃AIN0₃ bright yellow and the LDHMAO and polymethylaluminoxane supported complexes pale yellow.

For solid MAO, a W:AI mole ratio of 1 :150 was used. For all the others supports, 5% of the compound by weight was supported on the support (i.e. 5 mg on 100 mg of solid).

The supporting of W(NDipp)CI (THF) on silica is illustrated schematically below:

ca

The supporting of W(NDipp)CI₄(THF) on on Mg₃AI- S0₄, N0₃ and C0₃ LDHs is illustrated schematically below:

Mg₃AI(OH)

co₃ ²-, NO3-,

The supporting of W(NDipp)CI₄(THF) on solid MAO is illustrated schematically below:

Oligomerisation results

[00163] Figure 47 shows homogeneous oligomerisation of ethylene (1 bar) using W(N(C₆H₄OMe))Me3CI (depicted in Figure 43) at various temperatures. The results show that W(N(C6H₄OMe))Me3CI is an effective ethylene oligomerisation catalyst at temperatures ranging from 50-100°C, in particular towards the lower end of this range.

[00164] Figure 48 and Table 10 below compares the ability of various supported and unsupported W(NDipp)CI (THF) catalysts to catalyse the oligomerisation of ethylene. Fig. 48 shows that the catalytic composition afforded when W(NDipp)CI (THF) is supported on polymethylaluminoxane is noticeably more active than the unsupported complex ('homogeneous 1 :2') and the silica- and LDH-supported complexes. In particular, figure 48 shows that when polymethylaluminoxane is used as the support material, the oligomerisation of ethylene is up to 7 times that seen for homogeneous reaction (i.e. unsupported W(NDipp)CI₄(THF)).

- Turnover numbers (TONs) for the complex formed when W(NDipp)Cl₄(THF) ^' su orted on polymethylaluminoxane, silica and MgAIS0₄.

[00165] Figure 49 compares the ability of various polymethylaluminoxane-supported tungsten imido complexes to catalyse the oligomerisation of ethylene. In particular, Figure 49 shows that the catalytic composition afforded when W(NC₆H₃(3,5- CF₃))CI₄(THF) is supported on polymethylaluminoxane is up to 12 times more catalytically active than the catalytic composition afforded when W(N2,6-xylyl)CI₄(THF) is supported on polymethylaluminoxane, which suggests that the electronic effect of the imido group has a strong influence on the catalytic characteristics.

[00166] Figure 50 shows heterogeneous oligomerisation of ethylene using the complex afforded when W(N(C₆H₄OMe))CI (THF) is supported on polymethylaluminoxane at various temperatures. The data show that the highest turnover is achieved when the oligomerisation reaction is conducted at 50 °C. [00167] Table 1 1 below shows the catalytic properties of the complex formed when W(0)CU (not a compound of the invention) is supported on solid MAO.

Table 1 1. Turnover numbers for W(0)CU supported on polymethylaluminoxane at 100 V in C₆D₆ and 1 bar ethylene.

[00168] The data presented in Table 1 1 demonstrate that reference compound W(0)CI₄, when supported on solid MAO, is considerably less active than the compounds and compositions of the invention in catalysing the oligomerisation of ethylene to butene, and is also significantly less selective for 1 -butene.

[00169] While specific embodiments of the invention have been described for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS A process for forming alkene oligomers by oligomerisation, the process comprising the step of reacting alkene monomers in the presence of either:

a) a compound of the formula I shown below:

(I)

wherein:

W is tungsten;

bond b is a multiple bond;

X is an anionic ligand;

with the proviso that:

(i) when Q is 0->LA, Z is absent;

(ii) at least one of Ri , R₂ or R₃ is a group other than halo; and (iii) when bond a is a double bond one of R₂, R3 or X is absent;

or b) a catalytic composition comprising a compound of formula I and either: (i) a solid support or an activator; or (ii) both a solid support and an activator.

2. The process of claim 1 , wherein Q is N.

3. The process of claim 1 or 2, wherein bond a is a single bond.

4. The process of claim 1 , 2 or 3, wherein Ri , R₂ and R₃ are independently selected from methyl or a group of the formula:

wherein R_d, is selected from a (1 -2C)alkyl.

5. The process of any preceding claim, wherein Ri , R₂ and R₃ are methyl.

6. The process of any preceding claim, wherein X is selected from halo, OAc, hydride, phosphonate, sulphonate, borate, cyclopentadienyl,

pentamethylcyclopentadienyl, indenyl, pentamethylindenyl or (1 -4C)alkoxy.

7. The process of any preceding claim, wherein X is CI.

8. The process of any preceding claim, wherein Z is selected from:

a) (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2- 6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,OR_b, NR_bR_c, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl,

trifluoromethoxy, haloalkyl, and wherein R_b and R_c are independently selected from H or (1 -6C)alkyl; or b) phenyl substituted with 1 , 2 or 3 substituents selected from methyl, halo, methoxy and trifluoromethyl.

9. The process of any preceding claim, wherein Z is selected from:

a) a group of the formula:

wherein

R_e and Rf are independently selected from (2-6C)alkyl, ORh or NRhRi, wherein Rh and R, are independently selected from H or (1 - 6C)alkyl; or

b) phenyl substituted with 1 , 2 or 3 substituents selected from methyl, halo, methoxy and trifluoromethyl.

10. The process of any preceding claim, wherein Z is selected from:

1 1 . The process of any preceding claim, wherein Z is selected from:

12. The process of any preceding claim, wherein the compound of formula (I) has any of the following structures:

13. The process of any preceding claim, wherein the solid support is selected from silica, silica-MAO, polymethylalumioxane, a layered double hydroxide, LDH-MAO, aqueous miscible organic layered double hydroxides (AMO-LDHs), zirconia or titania.

14. The process of any preceding claim, wherein the solid support is selected from silica-MAO, polymethylalumioxane, a layered double hydroxide, LDH-MAO and aqueous miscible organic layered double hydroxides (AMO-LDHs).

15. The process of any preceding claim, wherein the solid support is

polymethylaluminoxane.

16. The process of any preceding claim, wherein the activator is selected from

trimethylaluminium (TMA), methylaluminoxane (MAO), polymethylaluminoxane, tri(isobutyl)aluminium (TIBA) or triethylaluminium (TEA).

17. The process of any preceding claim, wherein the step of reacting the alkene

monomers in the presence of either the compound of formula (I) or the catalytic composition is conducted at a temperature of 40-120 °C.

18. The process of any preceding claim, wherein the step of reacting the alkene

monomers in the presence of either the compound of formula (I) or the catalytic composition is conducted at a temperature of 40-80 °C.

19. The process of any preceding claim, wherein the alkene monomers are ethene monomers.

20. The process of any preceding claim, wherein the alkene oligomers comprise 2-6 repeat monomeric units based on the alkene monomers.

21 . The process of any preceding claim, wherein the alkene oligomers are dimers of the alkene monomers.

22. The process of any preceding claim, wherein the alkene oligomers are 1 -butene and 2-butene.

23. The process of any preceding claim, wherein the ethene monomers are reacted with the compound of formula (I) in a homogeneous state.

24. The process of any preceding claim, wherein the ethene monomers are reacted with the catalytic composition in a heterogeneous state.

25. A catalytic composition comprising

a) a compound of formula I as defined in any preceding claim; and b) a solid support selected from silica, MAO-activated silica,

polymethylalumioxane, a layered double hydroxide (LDH), LDH-MAO, aqueous miscible organic layered double hydroxides (AMO-LDHs), zirconia and titania.

26. The composition of claim 25, wherein the solid support is selected MAO-activated silica, polymethylalumioxane, a layered double hydroxide (LDH), LDH-MAO, and aqueous miscible organic layered double hydroxides (AMO-LDHs).

27. The composition of claim 25 or 26 wherein the solid support is selected from polymethylalumioxane, a layered double hydroxide (LDH), LDH-MAO, and aqueous miscible organic layered double hydroxides (AMO-LDHs).

28. The composition of claim 25, 26 or 27, wherein the solid support is

polymethylalumioxane.

29. A compound of formula (I) defined in claim 1 , wherein Q is N;

bond b is a double bond;

Ri , R2 and R₃ are methyl;

X is halo; and

Z is selected from:

i) (1 -6C)alkyl, cyclohexyl, SiMe₃, benzyl, naphthyl or a phenyl, wherein said phenyl is optionally substituted by one or more groups selected from (2-6C)alkyl, (3-6C)cycloalkyl, Si[(1 -4C)alkyl]₃, Si[0(1 -4C)alkyl)]₃,ORb, NR_bR_c, halo, amino, cyano, nitro, carboxy, carbamoyl, sulphamoyl, trifluoromethoxy, haloalkyl, and wherein Rb and R_c are independently selected from H or (1 -6C)alkyl; or ii) phenyl substituted with 1 or 3 methyl substituents, or 1 , 2 or 3 substituents selected from halo, methoxy and trifluoromethyl.

30. The compound of claim 29, wherein Z is selected from:

i. a group of the formula:

wherein R_e and Rf are independently selected from (2-6C)alkyl, ORh or NRhRi, wherein R_h and R, are independently selected from H or (1 -6C)alkyl; or

ii. phenyl substituted with 1 or 3 methyl substituents, or 1 , 2 or 3

substituents selected from halo, methoxy and trifluoromethyl.

31 . The compound of claim 29 or 30, wherein the compound is selected from:

59