The electrochemical reduction of H4Ru4(CO)(12) in tetrahydrofuran (THF
) is studied by means of de and ac polarography, cyclic voltammetry, a
nd FT-IR spectroscopy following electrolysis in a optically transparen
t 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 read
ily take place by electrochemical initiation and produce mono- and bis
ubstituted derivatives in yields depending on PPh(3) concentration. Th
e 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.