Rhenium(V) complexes with bidentate N,O-donor imidazole derivatives

The reaction of a two-fold molar excess of the potential N,O-donor ligand 2-(hydroxymethyl)-1-methylimidazole (Hmi) with trans-[ReOCl3(PPh3)(2)] led to the isolation of cis-[ReOCl2(mi)(PPh3)]. An X-ray structure determination indicated that the complex has distorted octahedral geometry, and that mi coordinates as a bidentate with the alcoholate oxygen trans to the oxo group. A similar reaction with 2-(1-ethyloxomethyl)-1-methylimidazole (eomi), the ethyl substituted analogue of Hmi, led to the formation of the oxo-bridged dinuclear complex [(mu-O){ReOCl2(eomi)(2)}(2)]. The ligand eomi coordinates as a monodentate via the imidazole nitrogen, with the "hard" ether oxygen uncoordinated. An X-ray crystal structure indicates that the chlorides are trans to each other in the ReN2Cl2 planes, which are orthogonal to the O=Re-O-Re=O backbone.