Reactions of trimethylsilylcyclopentadiene derivatives with titanium, niobium, and tantalum halides

Abstract

The use of trimethylsilyl derivatives as effective reagents for the new or improved syntheses of complexes of the early transition metals is described. Improved routes, involving the use of trimethylsilylcyclopentadiene, are described for the syntheses of [TiCl3(cp)], [TiBr3(cp)], [Til3(cp)], [NbCl4(cp)], and [TaCl4(cp)](cp = cyclopentadienyl). Routes, involving the use of bis(trimethylsilyl)cyclopentadiene, are described for the syntheses of the analogous complexes [TiX3(Me3Si-η-C5H4)], where X = Cl, Br, or l. The reactions of [TiCl3(cp)], [TiBr3(cp)], and [TiCl3(Me3Si-η-C5H4)] with a variety of bidentate ligands are described. The Lewis acidity of these titanium compounds is much reduced from that of the parent tetrahalides and only two adducts have been positively identified: these are [TiCl3(cp)]·phen (phen =o-phenanthroline) and [TiCl3(Me3Si-η-C5H4)]·pdma (pdma =o-phenylenebisdimethylarsine).