Synthesis of cationic alkyl bis(cyclopentadienyl)titanium complexes by one-electron oxidation of titanium(III) alkyls. The structure of [Cp2*TiMe(THF)]BPh4 and [Cp2*Ti(OH)(H2O)]BPh4·2THF

Abstract

The reaction of Cp2*TiMe (Cp* = C5Me5) with AgBPh4 in THF gives [Cp2*TiMe(THF)]BPh4 (1). The sterically congested complex contains a labile THF ligand which is easily displaced by donor molecules. Compound 1 reacts with traces of moisture to give the hydroxo complex [Cp2*Ti(OH)(H2O)]BPh4·2THF (2). The structures of both complexes have been determined by X-ray diffraction. The THF ligand in 1 is oriented parallel to the MeTiO plane; the TiO (THF) distance is 0.95 Å longer than the titanium-methyl bond. By contrast, the short TiOH distance in 2 (1.853 Å) indicates substantial TiO double bond character. The more weakly bound water ligand is associated with two THF molecules through strong hydrogen bonds.