Patent ID: 7307177

Claim:
A metallocene complex represented by the formula (C p R 5 ) n MX k where each occurrence of C p is a cyclopentadienyl group; each of the five R substituents on the cyclopentadienyl group is independently selected from the group consisting of hydrogen, C 1 to C 30 substituted or unsubstituted hydrocarbyl, halohydrocarbyl, silylhydrocarbyl, silylhalohydrocarbyl, and SiR′ 2 NR″ 2 where each of the two R′ substituents is independently selected from the group consisting of C 1 to C 30 substituted or unsubstituted hydrocarbyl, halohydrocarbyl, silylhydrocarbyl, and silylhalohydrocarbyl, wherein two adjacent R′ substituents may be joined to form part of a saturated, partially unsaturated or aromatic monocyclic or polycyclic ring structure, and each of the two R″ substituents is independently selected from the group consisting of C 3 to C 30 substituted or unsubstituted hydrocarbyl, halohydrocarbyl, silylhydrocarbyl and silylhalohydrocarbyl, wherein two adjacent R″ substituents may be joined to form part of a saturated, partially unsaturated or aromatic monocyclic or polycyclic ring structure, and where a R′ and a R″ may join together to form part of a monocyclic or polycyclic ring structure, and wherein two adjacent R substituents on a cyclopentadienyl group may be joined to form part of a saturated, partially unsaturated or aromatic monocyclic or polycyclic ring structure; n is 1 or 2; M is a metal of valence m from Group 4 of the Periodic Table of Elements, k is equal to m minus n and is 2 or 3 where m is the valence of M; and each X substituent is a univalent anionic ligand, or two X substituents are joined and bound to the metal atom to form a metallocycle ring, or two X substituents are joined to form a chelating ligand, a diene ligand, or an alkylidene ligand, provided that: (1) at least one R substituent on the cyclopentadienyl group is SiR′ 2 NR″ 2 ; and (2) the C p may be bridged by a bridging group to another C p group where the bridging group replaces one R group on the C p group(s) or the C p may be bridged by a bridging group to a heteroatom containing group where the bridging group replaces a hydrogen on the heteratom containing group; and (3) when n is 2, M is Hf or Zr.