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Influence of the Dithiolate Bridge on the Oxidative Processes of Diiron Models Related to the Active Site of [FeFe] Hydrogenases
Author(s) -
Arrigoni Federica,
Mohamed Bouh Salma,
De Gioia Luca,
Elleouet Catherine,
Pétillon François Y.,
Schollhammer Philippe,
Zampella Giuseppe
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201605060
Subject(s) - chemistry , dication , density functional theory , redox , reactivity (psychology) , electrochemistry , oxidation state , hydrogenase , amine gas treating , photochemistry , active site , crystallography , computational chemistry , catalysis , inorganic chemistry , molecule , organic chemistry , medicine , alternative medicine , electrode , pathology
Electrochemical studies of [Fe 2 (CO) 4 (κ 2 ‐dmpe)(μ‐dithiolate)] (dithiolate=adt Bn , pdt) and density functional theory (DFT) calculations reveal the striking influence of an amine functionality in the dithiolate bridge on their oxidative properties. [Fe 2 (CO) 4 (κ 2 ‐dmpe)(μ‐adt Bn )] ( 1 ) undergoes two one‐electron oxidation steps, with the first being partially reversible and the second irreversible. When the adt Bn bridge is replaced with pdt, a shift of 60 mV towards more positive potentials is observed for the first oxidation whereas 290 mV separate the oxidation potentials of the two cations. Under CO, oxidation of azadithiolate compound 1 occurs according to an ECE process whereas an EC mechanism takes place for the propanedithiolate species 2 . The dication species [ 1 ‐CO] 2+ resulting from the two‐electron oxidation of 1 has been spectroscopically and structurally characterized. The molecular details underlying the reactivity of oxidized species have been explored by DFT calculations. The differences in the behaviors of 1 and 2 are mainly due to the presence, or not, of favored interactions between the dithiolate bridge and the diiron site depending on the redox states, Fe I Fe II or Fe II Fe II , of the complexes.