Formation of the Distinct Redox-Interrelated Forms of Nitric Oxide from Reaction of Dinitrosyl Iron Complexes (DNICs) and Substitution Ligands

• Published in: Chemistry : a European journal 2010-07, Vol.16 (27), p.8088-8095
• Main Authors: Lu, Tsai-Te, Chen, Chih-Hao, Liaw, Wen-Feng
• Format: Article
• Language: English
• Subjects: bioinorganic chemistry; Chemistry; Cooperation; Formations; Iron; Iron - chemistry; ligand effects; Ligands; Models, Molecular; Molecular Structure; nitric oxide; Nitric Oxide - chemical synthesis; Nitric Oxide - chemistry; Nitrogen Oxides - chemistry; Oxidation-Reduction; Radicals; redox chemistry; SNAP; Stoichiometry; Transformations
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201000524

Release of the distinct NO redox‐interrelated forms (NO+, .NO, and HNO/NO−), derived from reaction of the dinitrosyl iron complex (DNIC) [(NO)2Fe(C12H8N)2]− (1) (C12H8N=carbazolate) and the substitution ligands (S2CNMe2)2, [SC6H4‐o‐NHC(O)(C5H4N)]2 ((PyPepS)2), and P(C6H3‐3‐SiMe3‐2‐SH)3 ([P(SH)3]), respectively, was demonstrated. In contrast to the reaction of (PyPepS)2 and DNIC 1 in a 1:1 stoichiometry that induces the release of an NO radical and the formation of complex [PPN][Fe(PyPepS)2] (4), the incoming substitution ligand (S2CNMe2)2 triggered the transformation of DNIC 1 into complex [(NO)Fe(S2CNMe2)2] (2) along with N‐nitrosocarbazole (3). The subsequent nitrosation of N‐acetylpenicillamine (NAP) by N‐nitrosocarbazole (3) to produce S‐nitroso‐N‐acetylpenicillamine (SNAP) may signify the possible formation pathway of S‐nitrosothiols from DNICs by means of transnitrosation of N‐nitrosamines. Protonation of DNIC 1 by [P(SH)3] triggers the release of HNO and the generation of complex [PPN][Fe(NO)P(C6H3‐3‐SiMe3‐2‐S)3] (5). In a similar fashion, the nucleophilic attack of the chelating ligand P(C6H3‐3‐SiMe3‐2‐SNa)3 ([P(SNa)3]) on DNIC 1 resulted in the direct release of [NO]− captured by [(15NO)Fe(SPh)3]−, thus leading to [(15NO)(14NO)Fe(SPh)2]−. These results illustrate one aspect of how the incoming substitution ligands ((S2CNMe2)2 vs. (PyPepS)2 vs. [P(SH)3]/[P(SNa)3]) in cooperation with the carbazolate‐coordinated ligands of DNIC 1 function to control the release of NO+, .NO, or [NO]− from DNIC 1 upon reaction of complex 1 and the substitution ligands. Also, these results signify that DNICs may act as an intermediary of NO in the redox signaling processes by providing the distinct redox‐interrelated forms of NO to interact with different NO‐responsive targets in biological systems. Accept NO substitute! Incoming substitution ligands play a key role in modulating the generation of the distinct redox‐interrelated forms of NO (N‐nitrosocarbazole, .NO, and HNO/NO−) derived from reactions of the dinitrosyl iron complex [(NO)2Fe(C12H8N)2]− and ligands (S2CNMe2)2, (PyPepS)2, and P(C6H3‐3‐SiMe3‐2‐SH)3, respectively (see scheme).