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Peroxide oxygenation of μ-thiolate−μ-sulfide Mo(V) dimer complexes of the type [Mo2(NAr)2(S2P(OEt)2)2(μ-O2CMe)(μ-SR)(μ-S)] yielded Mo2(μ-SO) and Mo2(μ-SO2) complexes, demonstrating the reactivity sequence μ-S > μ-SO ≫ μ-SR. Inversion isomers of the pyramidal sulfur site in the μ-SO bridge were observed, and the pyramidicity was confirmed crystallographically. Visible light photolysis of the Mo2(μ-SO2) complex liberated SO from the SO2 bridge and produced Mo2(μ-O) compounds. Crystallography of analogous Mo2(μ-S), Mo2(μ-SO), Mo2(μ-SO2), and Mo2(μ-O) complexes provided structural comparisons related to variations in the bridge functionality. For 2, Mo2C31H44N2O6P2S6:  a = 13.604(5) Å, b = 15.280(4) Å, c = 12.502(2) Å, α = 93.36(2)°, β = 112.00 (2)°, γ = 76.01(2)°, triclinic, P1̄, Z = 2. For 3, Mo2C31H44N2O7P2S6:  a = 12.535(2) Å, b = 25.299(9) Å, c = 13.989(5) Å, β = 99.99(2)°, monoclinic, P21/n, Z = 4. For 4, Mo2C31H44N2O8P2S6:  a = 12.591(9) Å, b = 25.34(1) Å, c = 14.048(3) Å, β = 100.79(4)°, monoclinic, P21/n, Z = 4. For 5, Mo2C31H44N2O7P2S5:  a = 13.731(5) Å, b = 19.267(4) Å, c = 16.652(5) Å, β = 104.78(3)°, monoclinic, P21/n, Z = 4.

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Compounds of the general form [MO~(NA~)~(S~P(OC~H~)~)~S(O~CR)]~(S~) (Ar = C6Hs, p-C&CH,; R = alkyl, aryl) were prepared by the reaction of [MO(NA~)(S,P(OC~H~)~)S]~ with H 2 0 2 in the presence of a carboxylic acid. The compounds contain a disulfide linkage bridging in inter-and intradimer fashion, formed by the oxidation of two Mo2S?+ cores to give SMo2SSMo2S, formally equivalent to SMo2S' thiyl radical coupling. Mixed dimer-organic disulfides were prepared by the reaction of [Mo2-(NC6H4CH~)2(S2P(OC2H~)2)2S2(02ccH3)]with sulfenyl chlorides, R'SCI (R' = alkyl, aryl). The products, [Mo2-(NC6H4CH3)2(S2P(OC2Hs)2)2s(02ccH3)(ssR')], contain an unusual R'SS-linkage to the two Mo(V) sites within the dimer, representable by SMo,SSR', wherein the monosubstituted organic disulfide ion bridges by its @-sulfur. A bridge tetrasulfide, [MO,(NC~H~CH~)~(S~P(OC~H~)~)~S(~~CCH~)]~(S~), was prepared by the reaction of [ M O , ( N C~H~C H , ) , ( S~P (~C~H~)~)~S~-(02CCH3)]-with S2CI2 and contains the SMo2SSSSMo2S unit, in which the tetrasulfide bridges also in inter-and intradimer fashion via its terminal sulfur atoms. Most of the compounds show stereoisomers related by bridge sulfur inversion. Reactions with triphenylphosphine gave either desulfurization or reduction.

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