Three Distinct Redox States of an Oxo‐Bridged Dinuclear Ruthenium Complex

Abstract

AbstractA series of [{(terpy)(bpy)Ru}(μ‐O){Ru(bpy)(terpy)}]n+ ([RuORu]n+, terpy=2,2′;6′,2′′‐terpyridine, bpy=2,2′‐bipyridine) was systematically synthesized and characterized in three distinct redox states (n=3, 4, and 5 for RuII,III2 , RuIII,III2 , and RuIII,IV2 , respectively). The crystal structures of [RuORu]n+ (n=3, 4, 5) in all three redox states were successfully determined. X‐ray crystallography showed that the RuO distances and the Ru‐O‐Ru angles are mainly regulated by the oxidation states of the ruthenium centers. X‐ray crystallography and ESR spectra clearly revealed the detailed electronic structures of two mixed‐valence complexes, [RuIIIORuIV]5+ and [RuIIORuIII]3+, in which each unpaired electron is completely delocalized across the oxo‐bridged dinuclear core. These findings allow us to understand the systematic changes in structure and electronic state that accompany the changes in the redox state.