Synthesis and properties of unsolvated bis(cyclopentadienyl)titanium alumohydride. Structure of {[(η5-C5H5)2Ti(μ-H)]2[(η5-C5H5)Ti(μ-H2]Al3(μ-H4)(H)}2·C6H6 a 12-nuclear titanium aluminum hydride complex with a short AlAl bond length, and refined structure

Unsolvated bis(cyclopentadienyl)titanium alumohydride was synthesized by two methods: heterogeneous reaction between (Cp2TiCl)2 and LiAlH4 in toluene and desolvation of Cp2TiAlH4·Et2O in vacuum. In the presence of cyclohexene, Cp2TiAlH4 (1) synthesized by the first method transforms to the known complex [Cp2TiH2Al(H)(C5H4)TiCp(H)]2 (3). The desolvation reaction apparently yields (Cp2TiAlH4)2 (7). In toluene, 7 transforms to a 12-nuclear titanium aluminum hydride complex 8 with short AlAl distances. Complex 1 catalyzes the hydrometallation of ethylene to LiAlEt4 by LiAlH4. Complex 7, unsolvated (Cp2Ti)2AlH4Cl, and (Cp2TiAlH3OEt)2 were tested as catalysts in hexene-1 hydrogenation. Complexes LiAlEt4 and 8 were characterized by X-ray structure analysis.