Abstract
Reaction of [PPN] [Fe (CO) 3(NO)] and Se powder in a 1:6 molar ratio refluxed in THF at 70 °C proceeded to give the dinitrosyl iron complex [PPN] [Se5Fe (NO) 2] (1). Its EPR signal of g = 2.064 at 298 K confirmed existence of the odd electron in the {Fe (NO) 2}9 complex 1. It is known that DNICs, [(Scys)2Fe(NO)2]- possess the EPR characteristic of g = 2.03 in the biological system. Based on the facts of g value of 1 inconsistent with 2.03 and its inertness to release NO, these results imply much less possibility for existence of [(Secys)2Fe(NO)2]- in nature. In other words, the LMW-DNICs and protein-bound DNICs may not exist with selenocysteine residues of proteins as ligands. Upon reaction of complex 1 and S8 in THF, the facile conversion of complex 1 to [PPN] [S5Fe(NO)2] was displayed. Protonation/ oxidation/methylation of complexes 1/ [PPN] [S5Fe(NO)2] by HBF4 and [Cp2Fe] [BF4], respectively, in THF yielded the known Roussin’s black salts [PPN] [Fe4E3(NO)7] (E = Se (2), S). Obviously, complexes 1/ [PPN] [S5Fe(NO)2] can serve as a precursor to synthesize the Roussin’s black salt analogues. Reaction of complex 1 with 1 equivalent of disulfide (RS)2 yielded dinitrosyl iron complex [(RS)2Fe(NO)2]– (R = C7H4SN, o-C6H4NHCOCH3, C4H3S ).