Olefin polymerization catalysts.

The invention relates to a process for olefin polymerization comprising polymerising ethylene and a monomer selected from C3-CZ0 α-olefin and/or a C5-C20 diolefin in the presence of a catalyst system comprising (A) a compound of the general formula: or wherein M is Zr, Hf or Ti ; (C5H5-y-xRx) is a cyclopentadienyl ring which is substituted with from zero to five groups R, "x" is 1, 2, 3, 4 or 5 denoting the degree of substitution, and each R is, independently, a radical selected from a group consisting of C1-C20 hydrocarbyl radicals, C1-C20 substituted hydrocarbyl radicals wherein one or more hydrogen atoms are replaced by a halogen atom, C1-C20 hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from the Group IV A of the Periodic Table of Elements and halogen radicals or (C5H5-y-xRx) is a cyclopentadienyl ring in which two adjacent R-groups are joined from C4-C20 ring to give a saturated or unsaturated polycyclic cyclopentadienyl ligand ;(JR'z-1-y) is a heteroatom ligand in which J is an element with a coordination number of three from Group V A or an element with a coordination number of two from Group VI A of the Periodic Table of Elements, each R' is, independently, a radical selected from a group consisting of C1-C20 hydrocarbyl radicals, substituted C1-C20 hydrocarbyl radicals wherein one or more hydrogen atoms is replaced by a halogen atom, and "z" is the coordination number of the element J ; each Q or Q' is, independently any univalent anionic ligand or Q and Q' are a divalent anionic chelating agent; M' has the same meaning as M ;"y" is 0 or 1 when w is greater than 0 ; y is 1 when w is 0, when "y" is 1, B is covalent bridging group containing a Group IV A or V A element ; andL is a Lewis base where "w" denotes a number from 0 to 3 and (B) an alumoxane and (C) a reaction product or such a compound (A) aluminum alkyl and water to obtain a polymer having an Mw of 1000 to 5 million and an Mw/Mn of from 1.5 to 15.0.