Two decomposition mechanisms of nitrosyl iron complexes [Fe2(μ-SR)(NO)4]

Abstract

Two decomposition mechanisms of nitrosyl iron complexes (NICs) [Fe₂(μ-SR)(NO)₄] in aqueous medium are known. One mechanism (for instance, in the case of complex [Fe₂(μ-SC₄H₃N₂)₂(NO)₄]) involves irreversible and rapid hydrolysis of NIC with the NO release accompanied with the formation of the products of further NO transformations. In the other mechanism (for instance, in the case of complexes [Fe₂(μ-S(CH₂)₂NH₃)₂(NO)₄]SO₄• •2.5H₂O and [Fe₂(μ-SC₅H₁₁NO₂)₂(NO)₄]SO₄•5H₂O), no hydrolysis occurs but NICs reversibly dissociate to release both NO and thiolate ligand into the medium. In the present work, the difference in the mechanisms of the NIC decomposition is explained by the difference in the NIC redox potentials. The experimental evidences of this fact are given.