The S-S bond-activation of diorganyl disulfide by the anionic metal carbonyl fragment [Mn(CO)5]− gives rise to an extensive chemistry. Oxidative decarbonylation addition of 2,2′-dithiobis(pyridine-N-oxide) to [Mn(CO)5]−, followed by chelation and metal-center oxidation, led to the formation of [MnII(-SC5H4NO-)3]− (1). The effective magnetic moment in solid state by SQUID magnetometer was 5.88 μB for complex 1, which is consistent with the MnII having a high-spin d5 electronic configuration in an octahedral ligand field. The average Mn(II)-S, S-C and N-O bond lengths of 2.581(1), 1.692(4) and 1.326(4) Å, respectively, indicate that the negative charge of the bidentate 1-oxo-2-thiopyridinato [SC5H4NO]− ligand in complex 1 is mainly localized on the oxygen atom. The results are consistent with thiolate-donor [-SC5H4NO]− stabilization of the lower oxidation state of manganese (Mn(I)), while the O,S-chelating [-SC5H4NO-]− ligand enhances the stability of manganese in the higher oxidation state (Mn(II)). Activation of S-S bond as well as O-H bond of 2,2′-dithiosalicylic acid by [Mn(CO)5]− yielded [(CO)3Mn(μ-SC6H4-C(O)-O-)2Mn(CO)3]2− (4). Oxidative addition of bis(o-benzamidophenyl) disulfide to [Mn(CO)5]− resulted in the formation of cis-[Mn(CO)4(SR)2]− (R=C6H4NHCOPh) which was employed as a chelating metallo ligand to synthesize heterotrinuclear [(CO)3Mn(μ-SR)3Co(μ-SR)3Mn(CO)3]− (8) possessing a homoleptic hexathiolatocobalt(III) core.