Bimetallocyclic transition metal catalyst systems
AssigneeExxon Chemical Patents Inc.
InventorRichard Allen Fisher
Life of this patent
Estimating the term…
Abstract
This invention relates to single site catalyst systems comprising activated bimetallocyclic transition metal compounds, and the use of these catalyst systems for the polymerization of ethylenically and acetylenically unsaturated monomers. The bimetallocyclic compounds comprise two metal atoms, selected from the group consisting of Group 4 or Group 5 metal atoms, connected through two covalent bridging links so as to form a cyclic compound having delocalized bonding in the cyclic structure. The exemplary bimetallocyclic compound bis-M-(trimethylsilyl-methylidyne) tetrakis-(trimethylsilylmethyl) ditantalum activated with alumoxane and borate compounds is shown to be useful for preparing ethylene polymers having M.sub.n of at least 267,000 and MWD of about 2.3.
Claims19
A polymerization catalyst composition comprising the reaction product of a bimetallocyclic compound and a cocatalyst, wherein said bimetallocyclic compound comprises two members independently selected from the group consisting of the Group 4 and Group 5 metal atoms Ti, Zr, Hf, Nb, and Ta, those members connected through two covalent bridging links so as to form a cyclic compound having delocalized .pi.-bonding in the cyclic structure of said bimetallocyclic compound.
Dependencies are inferred from the claim text.