Mechanistic aspects of chain propagation and transfer for metallocene-catalyzed olefin polymerization

Olefin insertion into a transition metal-hydride bond and its microscopic reverse, β-hydrogen elimination from a metal alkyl constitutive key steps of chain growth and termination in olefin polymerization, is discussed. The relative rates of chain growth and termination determine the chain length of the resulting polymer and many important polyolefin properties. A program aimed at elucidating the relative rates of these fundamental processes is initiated. These investigations revealed that cyclopentadienyl substitution and the nature of the olefin (or alkyl) have a considerable effect on the rates of insertion and elimination.