Abstract
In modeling the inactive form NHase, reactions of [PPN] [(NO)Fe(S,S-C6H4)2](1) ({Fe(NO)}6) and H2O2 or O2 give the sulfinate product, [PPN] [(NO)Fe(S,SO2-C6H4) (S,S-C6H4)](3). In contrast, [PPN]2 [(NO)Fe(S,S-C6H4)2](6A)({Fe(NO)}6) is denitrosylated when reacting with O2. On the basis of the X-ray crystal structure, the bent ∠Fe-N-O in complex 6A implies the increase of electron density on NO π antibonding orbital promoting the reactivity of O2 and NO∙. However, both 1 and 6A produce the same dinuclear dinitrosyl iron complex (DNICs) [PPN][(NO)Fe(μ-S,S-C6H4)2Fe(NO)2 ] (7) when reacting with NO+. It thus appears that the variations of electronic environment between the two complexes show no selectivity toward NO+. The nitrosylation reaction not only gives a good mimic pattern of transformation of RS-NO into DNICs but also opens up the study of the dinuclear DNICs. By the same synthetic method, [PPN] [(NO)Fe(μ-S,SO2-C6H4) (μ-S,S-C6H4)Fe(NO)2](8), a new member of a class of dinuclear DNICs, is also synthesized. It is suggested from the X-ray crystal structure data, IR/UV spectroscopy, and related reactivities that the Fe(NO)2 serves as an electron donor. The electron-donation occurs from Fe(2) to Fe(1) via the shortening Fe(1)—Fe(2) distance assigned as an {Fe(NO)}7-{Fe(NO)2}9 electronic structure. Further studies of 7 by reacting with S8, [Fe(S,S-CNMe2) 3], and [PPN] [(S,S-CNMe2)] proved that the NO-releasing preference is modulated by different thiolate compounds/ligands.