Synthesis and properties of unsolvated bis(cyclopentadienyl)titanium alumohydride. Structure of {[(eta(5)-C5H5)(2)Ti(mu-H)](2)[(eta(5)-C5H5)Ti(mu-H-2]Al-3(mu-H-4)-(H)}(2)center dot C6H6 a 12-nuclear titanium aluminum hydridecomplex with a short Al-Al bond length, and refined structure of LiAlEt4

Unsolvated bis(cyclopentadienyl)titanium alumohydride was synthesized by tw o methods: heterogeneous reaction between (Cp2TiCl)(2) and LiAlH4 in toluen e and desolvation of Cp2TiAl4. Et2O in vacuum. In the presence of cyclohexe ne, Cp2TiAlH4 (1) synthesized by the first method transforms to the known c omplex [Cp2TiH2Al(H)(C5H4)TiCp(H)](2) (3). The desolvation reaction apparen tly yields (Cp2TiAlH4)(2) (7). In toluene, 7 transforms to a 12-nuclear tit anium aluminum hydride complex 8 with short Al-Al distances. Complex 1 cata lyzes the hydrometallation of ethylene to LiAlEt4 by LiAlH4. Complex 7, uns olvated (Cp2Ti)(2)AlH4Cl, and (Cp2TiAlH3OEt)(2) were tested as catalysts in hexene-1 hydrogenation. Complexes LiAlEt4 and 8 were characterized by X-ra y structure analysis. (C) 2000 Elsevier Science S.A. All rights reserved.