HOMOGENEOUS CHROMIUM CATALYSTS FOR OLEFIN POLYMERIZATION

Chromium-based heterogeneous catalysts are used extensively for the po lymerization of olefins. There are few homogeneous model systems that allow investigation of the reaction mechanisms and unique characterist ics of chromium catalysts. Coordinatively unsaturated paramagnetic chr omium alkyls containing a Cp(CrR)-R-III fragment (Cp* = eta(5)-C5Me5, pentamethylcyclopentadienyl) catalyze the polymerization of ethylene and alpha-olefins. Correlations between molecular structure and cataly tic activity are reviewed.