Stoichiometric O2 Oxidation of Bis(Thioether)(Octaethylporphyrinato)ruthenium(II) Complexes to the Corresponding Sulfoxide Species in Acidic Media. Structural Confirmation of S-Bonded Sulfoxides

Exposure to O(2) (or air) of a CH(2)Cl(2), benzene, or toluene solution containing PhCO(2)H and Ru(OEP)(RR'S)(2) (where OEP = the dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin, R = methyl, ethyl, or decyl, and R' = methyl or ethyl), at ambient conditions, results in the selective oxidation of the axial ligand(s) on the metalloporphyrin complex to the corresponding sulfoxide(s). For example, a CD(2)Cl(2) solution of Ru(OEP)(dms)(2) (dms = dimethyl sulfide) and PhCO(2)H, exposed to 1 atm of O(2) at approximately 20 degrees C for 35 h, is oxidized to Ru(OEP)(dmso)(2), and the intermediates Ru(OEP)(dms)(dmso), [Ru(OEP)(dms)(2)][PhCO(2)], and Ru(OEP)(dms)(PhCO(2)) are identified (s implies sulfur-bonded). Mechanisms invoking in situ formation of H(2)O(2), disproportionation of Ru(III) species, and Ru(IV)=O intermediates are proposed for the O(2) oxidation of the thioether ligands. X-ray analysis of Ru(OEP)(Et(2)SO)(2) confirms that the sulfoxides are S-bonded.