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Indexed by:期刊论文

Date of Publication:2009-07-01

Journal:JOURNAL OF ORGANOMETALLIC CHEMISTRY

Included Journals:SCIE

Volume:694

Issue:15

Page Number:2309-2314

ISSN No.:0022-328X

Key Words:Bioinorganic chemistry; Carboxy-functionalized phosphine; Decarboxylation; Diiron complex; Iron hydrogenase

Abstract:Two carboxy-functionalized diiron complexes [{(mu-SCH2)(2)X}{Fe(CO)(3)}{Fe(CO)(2)L}] (X = NC3H7, L = Ph2PCH2CH2COOH, 4; X = CH2, L = Ph2PCH2COOH, 5) were prepared, as biomimetic models of the [FeFe] hydrogenase active site, from the CO-replacement of [{(mu-SCH2)(2)NC3H7}Fe-2(CO)(6)] (1) and (mu-pdt)Fe-2(CO)(6) (2) by phosphine ligands in CH3CN at 40 degrees C, respectively. In contrast, the reaction of 1 with Ph2PCH2COOH under the same condition afforded complex [{(mu-SCH2)(2)NC3H7}{Fe(CO)(3)}{Fe- (CO)(2)(Ph2PCH3)}] (3) with a decarboxylated phosphine ligand. The molecular structures of complexes 3-5 were determined by X-ray crystallographic analyses, which show that they have similar frameworks with the phosphine ligand on the apical position. The interesting C-H center dot center dot center dot S contacts between the methylene hydrogen atoms of the PhCH2COOH ligand and the mu-S atoms of the pdt-bridge are found in the crystal of 5. According to the experimental evidence, a plausible mechanism, via sequential phosphine coordination, N-protonation, and decarboxylation steps, is proposed for the formation of 3 and for explanation of the contrastive reactivities of the adt- (2-aza-1,3-propanedithiolato) and the pdt-(1,3-propanedithiolato) bridged diiron complexes toward decarboxylation of the Ph2PCH2COOH ligand. (C) 2009 Elsevier B.V. All rights reserved.