Bromido[1-(eta(6)-4-tert-butylbenzyl)-3-(2,4,6-trimethylbenzyl)benzimidazol-2-ylidene]chloridoruthenium(II)

A new ruthenium complex, [RuBrCl(C28H32N2)], has been synthesized and characterized by elemental analysis, H-1 NMR, C-13 NMR, IR-spectroscopy and a single-crystal X-ray diffraction study. The Ru atom in this complex is best described as having a considerably distorted octahedral coordination environment with the arene occupying three coordination sites. Two further coordination sites are occupied by chloride and bromide ligands, while the sixth site is occupied by the carbene. The carbene portion of the ligand is a benzimidazole ring. This ring is connected to the C6H4C(CH3)(3) arene by a CH2 bridge. This leads to a system with very little apparent strain. The two halogen atoms are disordered between Br and Cl. Two partial Cl atoms share the same sites as two partial Br atoms so that the title compound effectively has one Cl and one Br atom. C-H center dot center dot center dot X (X = Cl, Br) hydrogen bonds help to stabilize the crystal structure.