Synthesis and Characterization of N-heterocyclic Carbene Complexes of Titanium(IV) and Titanium(III)

The synthesis and characterization of two N-heterocyclic carbene (NHC) complexes of titanium (IPr)Ti(NMe2)(2)Cl-2 (I) [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] and (IPr)(2)TiCl3 (2) are described. Reactions of one and two equivalents of IPr with Ti(NMe2)(2)Cl-2 and TiCl3(thf)(3) yield the mono-NHC titanium(IV) complex 1 and the bis-NHC titanium(III) complex 2, respectively. They feature distorted trigonal bipyramidal geometries. Short intramolecular Cl center dot center dot center dot C-NHC contacts arc observed in the X-ray single-crystal structures of 1 and 2.