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

Abstract

The electronic structure of the trinuclear compound [(Ph₃P)(OC)₂Ru{µ-C₆H₄ (NH)₂}Mo(CO)₂{µ-C₆ H₄(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-Hückel method and a graphic interface. The ability of the dianionic riders to donate eight electrons to adjacent metals is interpreted, similarly for related Ru₂ dimers, in terms of perturbation theory. The molecule’s distortion, from the highest possible C_2v to C₂ 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.

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