Influence of the CN Orientation on the Degree of Electron Delocalization of Ru-Ru-Ru Mixed-Valent Complexes.

Investigations on mixed-valent complexes in the Class II/Class III frontier have been a particularly interesting issue due to their special electron delocalization. In this work, a pair of cyanidometal-/isocyanidometal-bridged Ru-Ru-Ru compounds, cis -[Cp(dppe)Ru-B-Ru(dppe)Cp] 2+ (B = NCRu(bpy) 2 CN, 1 2+ ; B = CNRu(bpy) 2 NC, 2 2+ ; Cp = 1,3-cyclopentadienyl, dppe = 1,2-bis(diphenlyphosphine)ethane, bpy = 2,2'-bipyridine), and one-electron oxidized 1 3+ and 2 3+ were synthesized and well characterized. For the two-electron oxidized 1 4+ and 2 4+ , their Fourier transform infrared (FTIR) and UV-vis-NIR spectra were investigated by employing spectroelectrochemical methods. The time-dependent density-functional theory (TDDFT) calculations and the experimental results indicate that the one-/two-electron oxidized mixed-valent compounds belong to Class II-III systems.