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 [TiCl4(THF)(2)] (THF = tetrahydrofuran) and [CpTiCl3] (Cp = eta(5)-C5H5) to form the mono- and bis(imidazolin-2-iminato) titanium(IV) complexes [(ImAdRN)TiCl3] (4, R = Mes, Dipp), [Cp(Im(AdR)N)TiCl2] (5, R = Mes, Dipp), and [(ImAdRN)2TiCl2] (6, R = Mes, Dipp). The crystal structures of all compounds except 2b were determined by X-ray diffraction analysis.

Automated summary

A series of unsymmetrical N-heterocyclic carbene imidazoline and imidazolin-2-imine ligands were synthesized and their metal complexes were characterized by X-ray diffraction analysis, except for one compound.