Pi and Sigma Transition Metal Carbon Compounds as Catalysts for the Polymerization of Vinyl Monomers and Olefins

Abstract

Publisher Summary This chapter examines the relationship between the structure of organometallic compounds and their ability to polymerize vinyl monomers and olefins. The chapter identifies methods of synthesis for polymerization catalysts that are more selective and more active than the systems currently available. The π-complexes are the best known and are among the most stable transition metal alkyl compounds and include U (πC 8 H 8 ) 2 , Cr (πC 6 H 6 ) 2 , and Ti( πC 5 H 5 ) 2 . In these compounds, the bonding electrons are delocalized over all the carbon atoms in the ring giving a symmetrical molecule in which the metal–carbon bond distances are identical. Wilke's π-ally1 compounds are members of this class. In this molecule, each allyl group occupies the transposition with respect to each other, all three carbon atoms of the allyl group are equidistant from the metal atom, and each allyl group formally occupies two coordinate positions.