Oxygenation of a Ruthenium(II) Thiolate to a Ruthenium(II) Sulfinate Proceeds via Ruthenium(III)

Exposure of acetonitrile/methanol solutions of [PPN][Ru(DPPBT)3]
[PPN = bis(triphenylphosphoranylidene); DPPBT = 2-diphenylphosphinobenzene thiolate] to oxygen initiates metal-centered
oxidation, yielding the ruthenium(III) thiolate Ru(DPPBT)3. Ru(DPPBT)3 further reacts with oxygen, at sulfur, to give the
ruthenium(III) sulfinate complex [Ru(DPPBT-O2)2(DPPBT)], which
is reduced under ambient conditions to [PPN][Ru(DPPBT-O2)2(DPPBT)]. Ruthenium(II) sulfinate is the only product isolated from
acetonitrile/methanol. Yellow crystals of [PPN][Ru(DPPBT-O2)2(DPPBT)] were obtained. Ruthenium(III) sulfinate was isolated as
green prism-shaped crystals upon oxygenation of [PPN][Ru(DPPBT)3] in chlorobenzene/hexane. Electrochemical oxidation of
ruthenium(II) sulfinate yields the ruthenium(III) derivative, which is
rapidly reduced back to ruthenium(II) upon the addition of hydroxide.