Diiron chelate complexes relevant to the active site of the iron-only hydrogenase

Abstract : A novel unsymmetrically disubstituted propanedithiolate compound [Fe2(CO)4(κ2-dmpe)(μ-pdt)] (1) (pdt = SCH2CH2CH2S, dmpe = Me2PCH2CH2PMe2) was synthesized by treatment of [Fe2(CO)6(μ-pdt)] with dmpe in refluxing THF. Compound 1 was characterized by single-crystal X-ray diffraction analysis. Protonation of 1 with HBF4·Et2O in CH2Cl2 gave at room temperature the μ-hydrido derivative [Fe2(CO)4(κ2-dmpe)(μ-pdt)(μ-H)](BF4)] (2). At low temperature, 1H and 31P–{1H} NMR monitoring revealed the formation of a terminal hydride intermediate 3. Comparison of these results with those of a VT NMR study of the protonation of symmetrical compounds [Fe2(CO)4L2(μ-pdt)] [L = PMe3, P(OMe)3] suggests that in disubstituted bimetallic complexes [Fe2(CO)4L2(μ-pdt)], dissymmetry of the complex is required to observe terminal hydride species. Attempts to extend the series of chelate compounds [Fe2(CO)4(κ2-L2)(μ-pdt)] by using arphos (arphos = Ph2AsCH2CH2PPh2) were unsuccessful. Only mono- and disubstituted derivatives [Fe2(CO)6−n(Ph2AsCH2CH2PPh2)n(μ-pdt)] (n = 1, 4a; n = 2, 4b), featuring dangling arphos, were isolated under the same reaction conditions of formation of 1. Compound 4b was structurally characterized.
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Comptes Rendus Chimie, Elsevier Masson, 2008, 11 (8), pp.906 - 914. 〈10.1016/j.crci.2008.04.002〉
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Soumis le : vendredi 1 septembre 2017 - 16:07:18
Dernière modification le : mercredi 11 avril 2018 - 10:56:01

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Salah Ezzaher, Jean-François Capon, Frederic Gloaguen, Nelly Kervarec, François Y. Pétillon, et al.. Diiron chelate complexes relevant to the active site of the iron-only hydrogenase. Comptes Rendus Chimie, Elsevier Masson, 2008, 11 (8), pp.906 - 914. 〈10.1016/j.crci.2008.04.002〉. 〈hal-01580508〉

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