摘要
S-Nitrosation of the coordinated thiolate of dinitrosyl iron complexes (DNICs) to generate S-nitrosothiols (RSNOs) was demonstrated. Transformation of [{(NO) 2 Fe(μ-StBu)} 2 ] (1-tBuS) into the {Fe(NO) 2 } 9 DNIC [(NO) 2 Fe(StBu)(MeIm)] (2-MeIm) occurs under addition of 20 equiv of 1-methylimidazole (MeIm) into a solution of 1-tBuS in THF. The dynamic interconversion between {Fe(NO) 2 } 9 [(NO) 2 Fe(S-NAP)(dmso)] (2-dmso) (NAP=N-acetyl-D-penicillamine) and [{(NO) 2 Fe(μ-S-NAP)} 2 ] (1-NAP) was also observed in a solution of complex 1-NAP in DMSO. In contrast to the reaction of complex 2-MeIm and bis(dimethylthiocarbamoyl) disulfide ((DTC) 2 ) to yield {Fe(NO)} 7 [(NO)Fe(DTC) 2 ] (3) (DTC=S 2 CNMe 2 ) accompanied by (tBuS) 2 and NO (g) , transformation of {Fe(NO) 2 } 9 2-MeIm (2-dmso) into RSNOs (RS=tBuS, NAP-S) along with complex 3 induced by the Brønsted acid solution of (DTC) 2 demonstrated that Brønsted acid may play a critical role in triggering S-nitrosation of the coordinated thiolate of DNICs 2-MeIm (or 2-dmso) to produce RSNOs. That is, DNIC-mediated S-nitrosation requires a Brønsted acid-Lewis base pair to produce RSNO. Transformation of DNICs into RSNOs may only occur on the one-thiolate-containing {Fe(NO) 2 } 9 DNICs, in contrast to protonation of the two-thiolate-containing DNICs [(NO) 2 Fe(SR) 2 ] - by Brønsted acid to yield [{(NO) 2 Fe(μ-SR)} 2 ]. These results might rationalize that the known protein-Cys-SNO sites derived from DNICs were located adjacent to acid and base motifs, and no protein-bound SNO characterized to date has been directly derived from [protein-(cysteine) 2 Fe(NO) 2 ] in biology. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.