NO Reduction to N 2 O Triggered by a Dinuclear Dinitrosyl Iron Complex via the Associated Pathways of Hyponitrite Formation and NO Disproportionation

• Published in: Inorganic chemistry Vol. 60; no. 21; pp. 15874 - 15889
• Main Authors: Wu, Wun-Yan, Tsai, Ming-Li, Lai, Yi-An, Hsieh, Chieh-Hsin, Liaw, Wen-Feng
• Format: Journal Article
• Language: English
• Published: United States 01.11.2021
• Subjects: Coordination Complexes - chemical synthesis; Coordination Complexes - chemistry; Density Functional Theory; Iron - chemistry; Models, Molecular; Molecular Structure; Nitric Oxide - chemistry; Nitrites - chemistry; Nitrogen Oxides - chemistry; Nitrous Oxide - chemistry; Oxidation-Reduction
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.1c00541

In spite of the comprehensive study of the metal-mediated conversion of NO to N O disclosing the conceivable processes/mechanism in biological and biomimetic studies, in this study, the synthesis cycles and mechanism of NO reduction to N O triggered by the electronically localized dinuclear {Fe(NO) } -{Fe(NO) } dinitrosyl iron complex (DNIC) [Fe(NO) (μ-bdmap)Fe(NO) (THF)] ( ) (bdmap = 1,3- bis(dimethylamino)-2-propanolate) were investigated in detail. Reductive conversion of NO to N O triggered by complex in the presence of exogenous ·NO occurs via the simultaneous formation of hyponitrite-bound {[Fe (NO) (μ-bdmap)] (κ -N O )} ( ) and [NO ] -bridged [Fe (NO) (μ-bdmap)(μ-NO )] ( ) (NO disproportionation yielding N O and complex ). EPR/IR spectra, single-crystal X-ray diffraction, and the electrochemical study uncover the reversible redox transformation of {Fe(NO) } -{Fe(NO) } [Fe (NO) (μ-bdmap)(μ-OC H )] ( ) ↔ {Fe(NO) } -{Fe(NO) } ↔ {Fe(NO) } -{Fe(NO) } [Fe(NO) (μ-bdmap)Fe(NO) ] ( ) and characterize the formation of complex . Also, the synthesis study and DFT computation feature the detailed mechanism of electronically localized {Fe(NO) } -{Fe(NO) } DNIC reducing NO to N O via the associated hyponitrite-formation and NO-disproportionation pathways. Presumably, the THF-bound {Fe(NO) } unit of electronically localized {Fe(NO) } -{Fe(NO) } complex served as an electron buffering reservoir for accommodating electron redistribution, and the {Fe(NO) } unit of complex acted as an electron-transfer channel to drive exogeneous ·NO coordination to yield proposed relay intermediate κ -N,O-[NO] -bridged [Fe (NO) (μ-bdmap)(μ-NO)] ( ) for NO reduction to N O.