Titanium(III) compounds with eta(2)-pyrazolato ligands

The reduction of [L2TiCl2] (1) (L = 3,5-tert-butylpyrazolate) with 1% Na/Hg in tetrahydrofuran (THP) affords the complex [L2TiCl(THF)(2)] (2), which crystallizes from hexane in moderate yield. The analogous reduction carried out in toluene gives dimeric [(L2TiCl)(2)] (3) in high yield. If the reduction time is extended to 3 days, the complex [L3Ti] (4) is isolated as light blue crystals in low yield. An alternative procedure for preparing compound 4 requires mixing [TiCl3(THF)(3)] with 3 equivalents of potassium 3,5-tert-butylpyrazolate in toluene. Crystallization from hexane affords 4 in high yield. Crystallographic data for 2, 3 and 4 are presented.