Electron spin resonance studies of Ziegler-type catalysts. Part I. Characterisation of a vanadium–aluminium complex obtained on mixing dichlorobis(η-cyclopentadienyl)vanadium with ethylaluminium dichloride

Abstract

Mixtures of dichlorobis(η-cyclopentadienyl)vanadium and ethylaluminium dichloride have been examined in methylene dichloride–heptane at Al : V ratios of 7 : 1. This system catalyses polymerisation of ethylene to give a polymer with good characteristics. Three species which exhibit e.s.r. spectra are present in this catalyst system, and one of these has been studied in detail by e.s.r. (room and glass temperature) and u.v. spectroscopy. The results show that this species, [Cl(cp)₂V(µ-Cl)₂AlCl₂](which is not catalytically active), has a trigonal-bipyramidal structure.