Reactivity pathways for nitric oxide and nitrosonium with iron complexes in biologically relevant sulfur coordination spheres

Synthesis and structure of dinitrosyl iron complexes with secondary thiolate bridging ligands [Fe2(μ-SCHR2)2(NO)4], R = Me, Ph

“…3 The formation of Roussin's red salt ester probably occurs via the stage of intermediate iron dinitrosyldicarbonyl Fe(NO) 2 (CO) 2 generation; this nitrosylated precursor is known to give DNICs when reacted with thiols [12,26] or with nitrogen containing bidentate aromatic ligands [38,39]. [19]. 4 We have analyzed the Mulliken charge distribution for RRSE with different substituents on thiolate sulfur (Table S1).…”

“…3 We have also prepared the complex with benzylthiolate ligand [Fe 2 (l-SBn) 2 (NO) 4 ] applying the same reaction conditions. The complex crystallized with the same cell parameters as in earlier published paper [19], but with 0.39% smaller R-factor (crystallographic data are presented in Table S4). 4 The comparison of geometrical parameters with previously synthesized complexes can be founds it Table S1 of Supporting information.…”

“…[23]. A complex with benzyl substituent at the sulfur bridging atom was described by Lippard and co-workers [19] and with the ethyl substituent, by Lu et al [27].…”

“…Today synthetic DNICs are suggested for use in medicine as NO donor pro-drugs [12]. Different synthetic ways are described for the dinuclear RRSE preparations: nitrosylation of Fe(II) and thiolate mixed solution with NO g [13]; S-alkylation of Roussin's red salt Na 2 [Fe 2 (l-S) 2 (NO) 4 4 ] are available with aliphatic [3,17], aromatic [18,19], peptide bound [20], and inorganic [21,22] substituents. Different ''aliphatic'' DNICs with primary [23,24] and tertiary [25,26] thiolate ligands are known, yet binuclear DNICs with secondary thiols (R 2 CH-SH) were not earlier structurally characterized by X-ray diffraction analysis.…”

13. Reactivity of iron-sulfur clusters with nitric oxide

“…When an Fe-S cluster complex, biological or synthetic reacts with NO, the iron-nitrosyl product that is preferentially formed depends on the nature of the cluster, the redox state of the source NO, the presence of excess thiol or thiolate, the nature of the solvent environment, and the stoichiometry of the reaction (Figures 5, 6 ) and RRE complexes (Fe2(µ-SR)2(NO)4) respectively, demonstrating the reliance of product species on the redox state of the NO source ( Figure 5) [96,97]. MNICs are widely accepted as intermediates in the stepwise nitrosylation of higher-order iron sulfur clusters en route to the more stable DNIC, RRE, and RBS products observed when NO is introduced in excess.…”