Molecular-orbital study of a quasi-linear Ru2Mo trinuclear compound with a diamidolene ligand across each metal-metal linkage

The electronic structure of the trinuclear compound [(Ph3P)(OC)(2)Ru{mu-C6H4(NH)(2)}Mo(CO)(2){mu-C6H4(NH)(2)}- Ru(CO)(2)(PPh3)], with a diamidolene ligand riding upright over each of the quasi-collinear Ru-Mo linkages, has been investigated by means of the extended-Huckel method and a graphic interface. The ability of the dianionic riders to donate eight electrons to adjacent metals is interpreted, similarly for related Ru, dimers, in terms of perturbation theory. The molecule's distortion, from the highest possible C-2v to C-2 symmetry was parametrized and the effects on the overall chemical bonding evaluated. The nature of the extended Ru-Mo-Ru linkage is addressed in some detail. The electronic redistribution over the ruthenium and molybdenum atoms is discussed in terms of their limiting oxidation states. Inferences are made as to the structure of a chromium analogue of the MoRu2 compound, as yet unknown.