Titanium complexes of π-coordinated thiophene derivatives

π-Coordinated tricarbonylchromium complexes of thiophene and benzothiophene are readily lithiated with butyllithium and reacted with titanocene dichloride to afford the binuclear complexes [Ti{(η1,η5-thienyl)Cr(CO)3}Cp2Cl] (1) and [Ti{(η1,η6-benzothienyl)Cr(CO)3}Cp2Cl] (5). These feature an activated chlorine ligand on the titanium moiety, which is easily substituted by a second π-coordinated arene precursor, thiols or water. Several novel bimetallic, trimetallic and tetrametallic complexes were synthesized exploiting this observation and are reported. Dilithiation of [Cr(η5-thienyl)(CO)3] and subsequent reaction with two equivalents of titanocene dichloride yielded the unstable η1,η1,η6-thienylene-bridged trinuclear complex, [{μ-Cr(η5-thienyl)(CO)3}{TiCp2Cl}2] (15), which was stabilized by replacing the chloro ligands by cyclohexylthiolato ligands. Crystals of the racemic mixture of [{(η1,η5-thienyl)Cr(CO)3}2TiCp2] (4) was subjected to a single crystal X-ray diffraction study and the presence of both enantiomers causes a thiophene ring to be disordered.