title: Formation pathway of Roussin's red ester (RRE) via the reaction of a {Fe(NO)2}(10) dinitrosyliron complex (DNIC) and thiol: facile synthetic route for synthesizing cysteine-containing DNIC.
abstract: Transformation of {Fe(NO)2}(10) dinitrosyliron complex (DNIC) Fe(CO)2(NO)2 into [{Fe(NO)2}(9)]2 Roussin's red ester (RRE) [(μ-S(CH2)2NH2)Fe(NO)2]2 (3) triggered by cysteamine via the reaction pathway (intermediates) [{Fe(NO)2}(10)]2[(NO)2Fe(μ-CO)(μ-S(CH2)2NH3)Fe(NO)2] (1) → {Fe(NO)2}(9){Fe(NO)2}(10)[(NO)2Fe(μ-S(CH2)2NH2)(μ-S(CH2)2NH3)Fe(NO)2] (2) → RRE 3 is demonstrated. The 1-to-2-to-3 conversion is promoted by proton transfer followed by O2 oxidation and deprotonation. Additionally, a study on facile conversion of complex 3 to complexes [(SR)(S(CH2)2NH3)Fe(NO)2] [SR = 2-aminoethanethiolate (4), benzenethiolate (5)] and [(CysS))(S(CH2)2NH3)Fe(NO)2] (6) via reaction with thiols and the further utility of complex 5 as a template for synthesizing mixed-thiolate-containing reduced RRE (rRRE) [(μ-SC6H5)(μ-S(CH2)2NH3)Fe2(NO)4] (7) provide the methodology for the synthesis and isolation of neutral, pure cysteine-/mixed-thiolate-containing DNIC/RRE. Compared to the conversion of complex 2 to complex 3 via reaction with O2, diphenyl disulfide triggers oxidation of complex 2 to lead to formation of the neutral {Fe(NO)2}(9) DNIC 5 and RRE 3. S-S bond activation of diphenyl disulfide by rRRE 2 may support the decay (oxidation) of rRRE species in ToMOC via the reduction of adjacent protein residues such as cystins, proposed by Lippard.
authors.affiliation: Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University , Hsinchu 30013, Taiwan.
authors.forename: Chung-Yen
authors.initials: CY
authors.lastname: Lu
authors.forename: Wen-Feng
authors.initials: WF
authors.lastname: Liaw
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D004952:Esters; D007501:Iron / Q000737:chemistry*; D015394:Molecular Structure; D009603:Nitroso Compounds / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D004952:Esters; D009603:Nitroso Compounds; D013438:Sulfhydryl Compounds; C028357:Roussin red methyl ester; D007501:Iron; D003545:Cysteine