| abstract |
The invention relates to a compound of the general formula:n wherein M is Zr, Hf or Ti;n (C 5 H 4-x R x ) is a cyclopentadienyl ring which is substituted with up zero to five groups R, "x" is 1, 2, 3 or 4 denoting the degree of substitution, and each substituent group R is, independently, a radical selected from a group consisting of C 1 -C 20 hydrocarbyl radicals, substituted C 1 -C 20 hydrocarbyl radicals wherein one or more hydrogen atoms are replaced by a halogen atom, an amido radical, a phosphido radical, an alkoxy radical or any other radical containing a Lewis acidic or basic functionality; C 1 -C 20 hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from the Group IV A of the Periodic Table of Elements; halogen radicals, amido radicals, phosphido radicals, alkoxy radicals, alkyl borido radicals or any other radicals containing Lewis acidic or basic functionality or (C 5 H 4 - x R x ) is a cyclopentadienyl ring in which two adjacent R-groups are joined from C 4 -C 2 o ring to give a saturated or unsaturated polycyclic cyclopentadienyl ligand; (JR' z - 2 ) 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, and each R' is, independently a radical selected from a group consisting of C 1 -C 20 hydrocarbyl radicals, substituted C,-C 2 o hydrocarbyl radicals, wherein one or more hydrogen atoms is replaced by a halogen atom, an amido radical, a phosphido radical and alkoxy radical or any other radical containing Lewis acidic or basic functionality 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, and M' has the same meaning as M; B is a covalent bridging group containing a Group IV A or V A element selected from dialkyl, alkylaryl or diaryl silicon or germanium radical alkyl or aryl phosphine or amine radical or a hydrocarbyl radical and L is a Lewis base where "w" denotes a number from 0 to 3. |