Electronic Interactions in Mixed-Valence Molecules As Mediated by Organic Bridging Groups

Article abstract of DOI:10.1021/ja00339a009

The preparations, spectroscopic properties, and electrochemistry of a number of new complexes with the general formula <(Ru(NH3)5)2L>ⁿ⁺ (n=4,5,6) are reported, where L is a rigid organic bridging ligand (including pyrimidine, the dicyanobenzenes, 3- and 4-cyanopyridine, and dicyanonaphthalenes).These complexes and others are used to illustrate several aspects of the effect of bridging ligand structure on metal-metal interactions in polymetallic systems.The observed trends are predicted theoretically by combining a molecular orbital description of the bridging ligand with a semiempirical measure of metal-ligand charge-transfer interactions.The relationship of bridging ligand size, orientation of substituents, interplanar distances and saturation to metal-metal interaction is demonstrated both theoretically and experimentally.Bridging ligand effects in intramolecular electron transfer are considered in the context of nonadiabatic theories and electronic interactions between redox sites.The relationship between the characteristics of the bridging group and the comproportional constant, K_c is discussed.