Preparation and Crystal Structure of Bis(tert-butyltetramethylcyclopentadienyl)dichlorotitanium

Abstract

[TiCl2(η5-C5Me4t-Bu)2] (1) was prepared by the reaction of [TiCl3(thf)3] with 2 equivalents of Li(η5-C5Me4t-Bu) (made by adding BuLi to a 1.33 molar excess of a mixture of tert-butyltetramethylcyclopentadiene isomers in THF) and subsequent oxidation of the Ti(III) intermediate to 1 by adding aqueous HCl. Neglecting the presence of cyclopentadiene isomers not forming the cyclopentadienide anion in the isomer mixture used for the synthesis of 1 resulted in the formation of hydrolytic product [{TiCl2(η5-C5Me4t-Bu)}2(μ-O)] (2) and a considerable decrease of yield of 1. The half sandwich complex [TiCl3(η5-C5Me4t-Bu)] (3) was obtained by synproportionation of 1 and TiCl4. Crystal structures of 1, 2, and 3 were determined. The electronic absorption spectra of 1 and 3 indicate a stronger electron-donor effect of tert-butyl group compared with methyl group.