Synthesis and Structures of Ti^III and Ti^IV Complexes Supported by a Bulky Guanidinate Ligand

In this work, titanium complexes of the bidentate bulky guanidine ligand [{(Dip)N}2CNR2]H (where Dip = C6H3iPr2-2,6 and R = CH(CH3)2) (LH) were prepared. Reaction of LH with one equivalent of [(CH3)2NTiCl3] underwent amine elimination to afford the monomeric complex [LTiCl3] (1) in high yield. Attempts to reduce 1 with potassium graphite (KC8) in tetrahydrofuran (THF) were unsuccessful. However, reacting 1 with 3.3 equivalents of KC8 in hexane led to the first example of structurally characterized mono-guanidinate ligand stabilized dimeric TiIII complex [LTiCl(μ–Cl)]2 (2). The synthesized complexes were characterized by NMR spectroscopy and the structures were further confirmed by X-ray crystallography