Formation of dinuclear titanium and zirconium complexes by olefin metathesis-catalytic preparation of organometallic catalyst systems

摘要

The titanium complex [(C_5H_4-allyl)TiCl_3] (2) undergoes olefin metathesis coupling when treated with 3 mol% of [Cl_2(L~1)(L~2)Ru = CHPh] (L~1 = L~2 = PCy_3, 4a; L~1 = PCy_3, L~2 = (H_2IMes), 4b) to yield the dimetallic complex [Cl_3Ti(C_5H_2)CH_2CH = CHCH_2-(C_5H_4)TiCl_3] (5). The allyl-substituted titanocene complex [Cp(C_5H_4-allyl)TiCl_2] (3) analogously yields the dimetallic system 6 when treated with 4. The ansa-zirconocene complex [Me_2Si(C_5H_4-allyl)ZrCl_2] (7) cleanly yields the analogous dimetallic coupling product 8 (> 95% isomerically pure), when treated with catalytic amounts of 4b in toluene. Complex 8 gives an active homogeneous ethene or propene polymerization catalyst, especially at elevated temperatures, when treated with excess methylalumoxane.