Nitrosyl iron complexes with enhanced NO donating ability: synthesis, structure and properties of a new type of salt with the DNIC cations [Fe(SC(NH2)2)2(NO)2]+

Abstract

Novel nitrosyl iron complexes [Fe(SC(NH₂)₂)₂(NO)₂]₂SO₄·H₂O(I) and [Fe(SC(NH₂)₂)₂(NO)₂]₂[Fe₂(S₂O₃)₂(NO)₄](II) have been synthesized via the reactions of FeSO₄ and Na₂[Fe₂(S₂O₃)₂(NO)₄], respectively, with acidic solutions of thiocarbamide in water. The structure and properties of I and II were studied using X-ray analysis, Mössbauer, IR, and EPR spectroscopy and amperometry. Both complexes are characterized by a prolonged NO generation without additional activation in aqueous anaerobic solutions, similar to the organic NO donor diethylene triamine; however, they are more effective: at pH 7 the NO amount is ∼32.6 and ∼31.8 nM mol⁻¹ of the complex for I and II, respectively. The obtained results show feasibility for the synthesis of water-soluble hybrid nitrosyl NO-generating complexes, which contain the NO groups both in the cationic and anionic sublattices and provide the control of the NO release kinetics.