New Examples of Half-Sandwich (Borylcyclopentadienyl)titanium Trichloride Complexes and an X-ray Structural Characterization of the Homobimetallic Complex [TiCl₃{η⁵-C₅H₄}]₂BPh

A new series of half-sandwich (borylcyclopentadienyl)titanium trichloride complexes have been prepared which include the boryl substituents [1,2-(C₆H₄O₂)]B−, Ph(Cl)B−, Ph₂B− and a (PhB<)-bridged bimetallic complex. No correlation was found between the ¹H and ¹³C NMR chemical shifts of the cyclopentadienyl ring in these complexes and the Lewis acidity of the attached boryl group. The crystal structure of the phenylboron-bridged bimetallic complex PhB{(η⁵-C₅H₄)TiCl₃}₂ was determined. The cyclopentadienyltitanium units of the molecule are twisted away from each other, forming an angle of 41° between the cyclopentadienyl ring planes. Each cyclopentadienyl ring is twisted out of the trigonal plane of the boron by 24°. Preliminary results concerning the Ti-alkylation of some of these complexes are described.