摘要
Dinitrosyl iron complex [(-SC 7 H 4 SN) 2 Fe(NO) 2 ] - (1) was prepared by reaction of [S 5 Fe(NO) 2 ] - and bis(2-benzothiozolyl) disulfide. In synthesis of the analogous dinitrosyl iron compounds (DNICs), the stronger electron-donating thiolates [RS] - (R = C 6 H 4 -o-NHCOCH 3 , C 4 H 3 S, C 6 H 4 NH 2 , Ph), compared to [-SC 7 H 4 SN] - of complex 1, trigger thiolate-ligand substitution to yield [(-SC 6 H 4 -o-NHCOCH 3 ) 2 Fe(NO) 2 ] - (2), [(-SC 4 H 3 S) 2 Fe(NO) 2 ] - (3), and [(SPh) 2 Fe(NO) 2 ] - (4), respectively. At 298 K, complexes 2 and 3 exhibit a well-resolved five-line EPR signal at g = 2.038 and 2.027, respectively, the characteristic g value of DNICs. The magnetic susceptibility fit indicates that the resonance hybrid of {Fe + ( • NO) 2 } 9 and {Fe - ( + NO) 2 } 9 in 2 is dynamic by temperature. The IR ν NO stretching frequencies (ranging from (1766, 1716) to (1737, 1693) cm -1 (THF)) of complexes 1-4 signal the entire window of possible electronic configurations for such stable and isolable {Fe(NO) 2 } 9 [(RS) 2 Fe(NO) 2 ] - . The NO-releasing ability of {Fe(NO) 2 } 9 [(RS) 2 Fe(NO) 2 ] - is finely tuned by the coordinated thiolate ligands. The less electron-donating thiolate ligands coordinated to {Fe(NO) 2 } 9 motif act as better NO-donor DNICs in the presence of NO-trapping agent [Fe(S,S-C 6 H 4 ) 2 ] 2 2- . Interconversion between {Fe(NO) 2 } 9 [(RS) 2 Fe(NO) 2 ] - and {Fe(NO) 2 } 10 [(Ph 3 P) 2 Fe(NO) 2 ] was verified in the reaction of (a) [(RS) 2 Fe(NO) 2 ] - , 10 equiv of PPh 3 and sodium-biphenyl, and (b) 2 equiv of thiol, [RS] - , and [(Ph 3 P) 2 Fe(NO) 2 ], respectively. The biomimetic reaction cycle, transformation between {Fe(NO) 2 } 9 [(RS) 2 Fe(NO) 2 ] - and {Fe(NO) 2 } 9 [(R′S) 2 Fe(NO) 2 ] - , reversible interconversion of {Fe(NO) 2 } 9 and {Fe(NO) 2 } 10 DNICs, and degradation/ reassembly of [2Fe-2S] clusters may decipher and predict the biological cycle of interconversion of {Fe(NO) 2 } 9 DNICs, {Fe(NO) 2 } 10 DNICs, and the [Fe-S] clusters in proteins. © 2005 American Chemical Society.