SYNTHESIS, STRUCTURE, AND HOMOGENEOUS CATALYTIC ACTIVITY OF THE NOVEL (CYCLOSILOXY)OXOVANADIUM(IV) COMPLEX VO(O(SIPH2O)2)2-MU-(LI(THF)2)2

Treatment of VCl4 with 3 molar equiv of the lithium compound [O(SiPh2OLi)2.2THF] gave the oxovanadium(IV) cyclosiloxane [VO{O(SiPh2O)2}2-mu-(Li-(THF)2]2.toluene, 1.toluene. Analogous reactions with the sodium compound [O(SiPh2ONa)2.2THF] however led only to intractable mixtures. Compound 1 is to our knowledge the first V(IV) metallasiloxane and was characterized spectroscopically by IR, UV/vis, ESR, and 1.toluene was characterized by a single-crystal X-ray study. It is an active precatalyst, in conjunction with AlMe3, for the polymerization of ethylene and a moderate catalyst for the polymerization of propylene.