INTERACTION OF CYCLOPENTADIENYLTITANIUM(IV) CHLORIDES WITH LITHIUM ALUMINUM-HYDRIDE

The interactions in the systems Cp2TiCl2/LiAlH4 and CpTiCl3/LiAlH4 have been studied by calorimetric titration and EPR techniques. There are four steps to each of these reactions corresponding to the following Cp2TiCl2 (CpTiCl3) to LiAlH4 ratios: 2/1 (reduction of titanium(IV) to titanium(III) and formation of trinuclear complexes Cp2TiH2AlCl2 · Cp2TiCl or Cp(Cl)TiH2AlCl2 · CpTiCl2), 1/1 (formation of dimers [Cp2TiH2AlH(Cl)]2 or [Cp(Cl)TiH2AlH(Cl)]2), 1/1.5 (replacement of a terminal chloro atom in the dimers and formation of (Cp2TiH2)2Al2H3Cl or (Cp(Cl)TiH2)2Al2H3Cl), and 1/2 (replacement of the remaining terminal chloro atom, dissociation of dimers and formation of unstable triple complexes Cp2TiH2AlH2 · AlH3 or Cp(Cl)TiH2AlH2 · AlH3). The catalytic properties of the system Cp2TiCl/LiAlH4 in the hydrogenation of cyclohexene and hex-1-ene are described. © 1979.