The five-coordinated iron-thiolate nitrosyl complexes [(NO)Fe(S,S-C6H3R)(2)](-) (R = H (1), m-CH3 (2)), [(NO)Fe-(S,S-C6H2-3,6-Cl-2)(2)](-) (3), [(NO)Fe(S,S-C6H3R)(2)](2-) (R = H (10), m-CH3 (11)), and [(NO)Fe(S,S-C6H2-3,6-Cl-2)(2)](2-) (12) have been isolated and structurally characterized. Sulfur oxygenation of iron-thiolate nitrosyl complexes 1-3 containing the {Fe(NO)}(6) core was triggered by O-2 to yield the S-bonded monosulfinate iron species [(NO)Fe(S,SO2-C6H3R)(S,S-C6H3R)](-) (R = H (4), m-CH3 (5)) and [(NO)Fe(S,SO2-C6H2-3,6-Cl-2)(S,S-C6H2-3,6-Cl-2)](2)(2-) (6), respectively. In contrast, attack of O-2 on the {Fe(NO)}(7) complex 10 led to the formation of complex 1 accompanied by the minor products, [Fe(S,S-C6H4)(2)](2)(2-) and [NO3](-) (yield 9%). Reduction of complexes 4-6 by [EtS](-) in CH3- CN-THF yielded [(NO)Fe(S,SO2-C6H3R)(S,S-C6H3R)](2-) (R = H (7), m-CH3 (8)) and [(NO)Fe(S,SO2-C6H2-3,6-Cl-2)- (S,S-C6H2-3,6-Cl-2)](2-) (9) along with (EtS)(2) identified by H-1 NMR. Compared to complex 10, complexes 7-9 with the less electron-donating sulfinate ligand coordinated to the {Fe(NO)}(7) core were oxidized by 02 to yield complexes 4-6. Obviously, the electronic perturbation of the {Fe(NO)}(7) core caused by the coordinated sulfinate in complexes 7-9 may serve to regulate the reactivity of complexes 7-9 toward O-2. The iron-sulfinate nitrosyl species with the {Fe(NO)}(6/7) core exhibit the photolabilization of sulfur-bound [O] moiety. Complexes 1-4-7-10 (or 2-5-8-11 and 3-6-9-12) are interconvertible under sulfur oxygenation, redox processes, and photolysis, respectively.