Reductions of β-Diketiminato−Titanium(III) Complexes

The reductions of (Nacnac)Ti(III) complexes (Nacnac = (HC(CMeNC6H3(i-Pr)2)2) are examined. Treatment of (Nacnac)TiCl2 with K/Na alloy in the presence of CH2(PPh2)2 afforded the dark red product [K(C(Me)CHC(Me)NAr)Ti(NAr)(μ-H)]2 (2). This Ti(III)-imido-hydride complex is a product of Nacnac ligand cleavage. The Ti(III) species (Nacnac)CpTiCl (3) and (Nacnac)(C5Me4H)TiCl (4) were prepared and characterized. While compound 3 was readily alkylated with n-BuLi to give (Nacnac)CpTiBu (5), reduction of 3 with Na/K gave the dinitrogen complex ((Nacnac)CpTi)2(μ-η2-N2) (6). In contrast, treatment of 4 with t-BuLi or n-BuLi or Na/K amalgam afforded the ligand cleavage product (C5Me4H)[(ArNC(Me)CHC(Me)]Ti(NAr) (7). Compounds 2−7 are crystallographically characterized. The effects of the nature of the ancillary ligands on the course of these reactions are considered.