Electrochemical-Behavior And Electron-Transfer Chain (Etc) Reactions Of H4ru4(Co)(12)

The electrochemical reduction of H4Ru4(CO)(12) in tetrahydrofuran (THF) is studied by means of de and ac polarography, cyclic voltammetry, and FT-IR spectroscopy following electrolysis in a optically transparent thin-layer electrochemical (OTTLE) cell. The reduction of the title complex generates a transient radical anion, [H4Ru4(CO)(12)](-), which produces the stable anion [H3Ru4(CO)(12)](-) On a longer time scale. In the presence of triphenylphosphine, nucleophilic substitutions readily take place by electrochemical initiation and produce mono- and bisubstituted derivatives in yields depending on PPh(3) concentration. The termination side chain reaction is the loss of a hydride ligand, to give the above-mentioned anion, which is inert to substitution even in the presence of a large excess of Lewis base.