Titanium complexes with unsymmetrically substituted imidazolin-2-iminato ligands.

The reaction of the unsymmetrical N-heterocyclic carbenes 1-(2,4,6-trimethylphenyl)-3-(adamantyl)imidazolin-2-ylidene (IAdMes, 1a) and 1-(2,6-diisopropylphenyl)-3-(adamantyl)imidazolin-2-ylidene (IAdDipp, 1b) with trimethylsilyl azide furnished the 2-(trimethylsilylimino)imidazolines 2a (Im AdMes NSiMe 3 ) and 2b (Im AdDipp NSiMe 3 ). Desilylation by stirring in methanol gave the corresponding imidazolin-2-imines 3a (Im AdMes NH) and 3b (Im AdDipp NH). 2a and 2b were treated with [TiCl 4 (THF) 2 ] (THF = tetrahydrofuran) and [CpTiCl 3 ] (Cp = η 5 -C 5 H 5 ) to form the mono- and bis(imidazolin-2-iminato) titanium(IV) complexes [(Im AdR N)TiCl 3 ] (4, R = Mes, Dipp), [Cp(Im AdR N)TiCl 2 ] (5, R = Mes, Dipp), and [(Im AdR N) 2 TiCl 2 ] (6, R = Mes, Dipp). The crystal structures of all compounds except 2b were determined by X-ray diffraction analysis.