A catalyst in solid particulate form free from an external carrier material comprising (I) a complex of formula (I) wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from —R′ 2 C—, —R′ 2 C—CR′ 2 —, —R′ 2 Si—, —R′ 2 Si—SiR′ 2 —, —R′ 2 Ge—, wherein each R′ is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl; each R 2 is independently hydrogen or a C1-C20 hydrocarbyl radical provided that at least one R 2 is not hydrogen; each R 5 is independently hydrogen or a C1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16; each R 6 is independently hydrogen or a C1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16; each n is independently 1, 2 or 3; and each R 8 is a C1-20 hydrocarbyl group; and (ii) a cocatalyst comprising a compound of a group 13 metal, e.g. Al or boron.
1. A catalyst in solid particulate form free from an external carrier material comprising
(i) a complex of formula (I)
wherein
M is zirconium or hafnium;
each X is a sigma ligand;
L is dimethylsilyl, diethylsilyl, ethylene or methylene;
each R 2 is independently hydrogen or a C1-C20 hydrocarbyl radical provided that at least one R 2 is not hydrogen;
each R 5 is independently hydrogen or a C1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16;
each R 6 is independently hydrogen or a C1-20 hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16;
each n is independently 1, 2 or 3; and
each R 8 is a C1-20 hydrocarbyl group;
and (ii) a cocatalyst comprising a compound of a group 13 metal.
2. The catalyst of claim 1 which is obtained by a process in which
(a) a liquid/liquid emulsion system is formed, said liquid/liquid emulsion system comprising a solution of the catalyst components (i) and (ii) dispersed in a solvent so as to form dispersed droplets; and
(b) solid particles are formed by solidifying said dispersed droplets.
3. A catalyst as claimed in claim 1 comprising a complex of formula
wherein
M is zirconium or hafnium;
each X is a sigma ligand;
L is dimethylsilyl, diethylsilyl, ethylene or methylene;
each R 2 is independently hydrogen or a C1-C20 hydrocarbyl radical provided that at least one R 2 is not hydrogen;
each R 5 is independently hydrogen or an aliphatic C1-20 hydrocarbyl group;
each R 6 is independently hydrogen or an aliphatic C1-20 hydrocarbyl group;
n is 1, 2 or 3; and
each R 8 is an aliphatic C1-20 hydrocarbyl group.
4. A catalyst as claimed in claim 1 comprising a complex of formula (II)
wherein
M is zirconium or hafnium;
each X is independently a hydrogen atom, a halogen atom, C 1-6 -alkoxy group, C 1-6 -alkyl, phenyl or benzyl group;
L is dimethylsilyl, diethylsilyl, ethylene or methylene;
each R 2 is a C1-10 alkyl group;
each R 5 is hydrogen or a C1-10 alkyl group;
each R 6 is hydrogen or a C1-10 alkyl group;
n is 1 to 3;
and each R 8 is a C1-20 hydrocarbyl group.
5. A catalyst as claimed in claim 1 comprising a complex of formula (III):
wherein
M is zirconium or hafnium;
each X is independently a hydrogen atom, a halogen atom, C 1-6 -alkoxy group, C 1-6 -alkyl, phenyl or benzyl group;
L is dimethylsilyl, diethylsilyl, ethylene or methylene;
R 2 is a C1-10 alkyl group;
n is 1 to 3;
and each R 8 is a C1-10 alkyl group or C6-10 aryl group.
6. A catalyst as claimed in claim 1 comprising a complex of formula (IV)
wherein L, M and X are as hereinbefore defined;
R 2 is methyl; and
R 8 is C3-8 alkyl.
7. A catalyst as claimed in claim 1 wherein L is dimethylsilyl, ethylene or methylene.
8. A catalyst as claimed in claim 1 comprising the complex rac-Me 2 Si[2-Me-4(3,5- t Bu 2 Ph)-Ind] 2 ZrCl 2 or rac-Me 2 Si[2-Me-4(3,5- t Bu 2 Ph)-Ind] 2 HfCl 2 .
9. A catalyst as claimed in claim 1 wherein said cocatalyst is aluminoxane.
10. A catalyst as claimed in claim 1 wherein the two ligands forming the complex are identical.