- Re-examination of the formation of dinitrosyl-iron complexes during reaction of S-nitrosothiols with Fe(II)
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The reaction of S-nitrosothiol compounds with ferrous ions in solution has been investigated and the generated dinitrosyl-iron complexes have been characterized. During the reaction of S-nitrosocysteamine with Fe(II) in water solution in the presence of a twofold excess (with respect to iron) of cysteamine hydrochloride (CSH), an EPR-silent dinuclear iron complex (complex A of formula [Fe2(RS)2(NO)4]) was formed as the major species and was characterized by FAB MS+, UV-Vis, NMR and IR spectroscopies. In the presence of a large excess of CSH (CSH/Fe(II)=20:1), a green paramagnetic mononuclear complex (complex B of formula [Fe(RS)2(NO)2]-) was formed. From EPR and UV-Vis data, and also on the basis of the few crystallographic structures known for similar complexes, complex B is proposed to display a distorted tetrahedral geometry (C2v), approaching a trigonal bipyramid with a missing ligand, with the unpaired electron mainly localized on the dz2 orbital of the iron characterized by a d9 electronic configuration.
- Costanzo, Simona,Ménage, Stephane,Purrello, Roberto,Bonomo, Raffaele P.,Fontecave, Marc
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