New Nitrosyl Derivatives of Diiron Dithiolates Related to the Active Site of the [FeFe]-Hydrogenases

Abstract : Nitrosyl derivatives of diiron dithiolato carbonyls have been prepared starting from the precursor Fe2(S2CnH2n)(dppv)(CO)4 (dppv = cis-1,2-bis(diphenylphosphinoethylene). These studies expand the range of substituted diiron(I) dithiolato carbonyl complexes. From [Fe2(S2C2H4)(CO)3(dppv)(NO)]BF4 ([1(CO)3]BF4), the following compounds were prepared: [1(CO)2(PMe3)]BF4, [1(CO)(dppv)]BF4, NEt4[1(CO)(CN)2], and 1(CO)(CN)(PMe3). Some of these substitution reactions occur via the addition of 2 equiv of the nucleophile followed by the dissociation of one nucleophile and decarbonylation. Such a double adduct was characterized crystallographically in the case of [Fe2(S2C2H4)(CO)3(dppv)(NO)(PMe3)2]BF4. This result shows that the addition of two ligands causes scission of the Fe−Fe bond and one Fe−S bond. When cyanide is the nucleophile, nitrosyl migrates away from the Fe(dppv) site, yielding a Fe(CN)2(NO) derivative. Compounds [1(CO)3]BF4, [1(CO)2(PMe3)]BF4, and [1(CO)(dppv)]BF4 were also prepared by the addition of NO+ to the di-, tri-, and tetrasubstituted precursors. In these cases, the NO+ appears to form an initial 36e− adduct containing terminal Fe−NO, followed by decarbonylation. Several complexes were prepared by the addition of NO to the mixed-valence Fe(I)Fe(II) derivatives. The diiron nitrosyl complexes reduce at mild potentials and in certain cases form weak adducts with CO. IR and EPR spectra of 1(CO)(dppv), generated by low-temperature reduction of [1(CO)(dppv)]BF4 with Co(C5Me5)2, indicates that the SOMO is located on the FeNO subunit.
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Inorganic Chemistry, American Chemical Society, 2008, 47 (24), pp.11816 - 11824. 〈10.1021/ic801542w〉
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Dernière modification le : jeudi 11 janvier 2018 - 06:17:06

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Matthew T. Olsen, Aaron K. Justice, Frederic Gloaguen, Thomas B. Rauchfuss, Scott R. Wilson. New Nitrosyl Derivatives of Diiron Dithiolates Related to the Active Site of the [FeFe]-Hydrogenases. Inorganic Chemistry, American Chemical Society, 2008, 47 (24), pp.11816 - 11824. 〈10.1021/ic801542w〉. 〈hal-01580530〉

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