Reductions of {RuNO}(6)-type nitrosyls. Characteristics of the two-electron reduction species isolated as a complex having a formally negatively charged mu-nitrosyl ({RuNO}(8)-{RuNO}(8)) and the one-electron reduction species generated electrochemically ({RuNO}(7))

The reaction between cis-[Ru(NO)(H2O)(bpy)(2)](3+) ({RuNO}(6)) and formic a cid gives [{Ru(mu-NO)}(2)(bpy)(4)](2+) (2) ({RuNO}(8)-{RuNO}(8)), along wit h some other products species: cis-[Ru(NO)(OCHO)(bpy)(2)](2+) (1)({RuNO}(6) ), and cis-[Ru(OCHO)(H2O)(bpy)(2)](+). The mu-nitrosyl complex (2) consists of two cis-Ru(bpy)(2) fragments connected by two formally negatively charg ed bridging nitrosyl ligands. Electrochemical study of the complex shows th at two successive one-electron oxidation waves to give [{Ru(mu-NO)}(2)(bpy) (4)](4+) ({RuNO}(7)-{RuNO}(7)) are found. The generated two-electron oxidat ion species is disintegrated to afford a one-electron reduction species, ci s- [Ru(NO.)(CH3CN)(bpy)(2)](2+) ({RuNO}(7)), along with a small amount of a n unexpected nitro species, cis-[Ru(NO2)(CH3CN)(bpy)(2)](+). The characteri stics of electrochemically generated one-electron reduction species cis-[Ru (NO.)X(bpy)(2)]((n-1)+) ({RuNO}(7)) (X = H2O, OCHO) are investigated in the connection. During the degradation process of the one-electron reduction s pecies, a nitrosyl-to-nitro conversion was found to proceed in cis-[Ru(NO.) (H2O)(bpy)(2)](2+), via the formation of cis-[Ru(NO.)(CH3CN)(bpy)(2)](2+) m entioned above; this is the first observation which explains the electroche mically-induced nitrosyl-to-nitro conversion observed in the reduction proc ess of {RuNO}(6)-type complexes.