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Indexed by:期刊论文

Date of Publication:2006-11-15

Journal:JOURNAL OF ORGANOMETALLIC CHEMISTRY

Included Journals:SCIE

Volume:691

Issue:23

Page Number:5045-5051

ISSN No.:0022-328X

Key Words:biomorganic chemistry; diiron dithiolate complexes; electrochemistry; iron-only hydrogenase; triazaphosphaadamantane ligand

Abstract:In order to improve the hydro- and protophilicity of the active site models of the Fe-only hydrogenases, three diiron dithiolate complexes with DAPTA ligand(s) (DAPTA=3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonanc), (mu-pdt)[Fe(CO)(2)][Fe(CO)(2)(DAPTA)] (1, pdt = 1,3-propanedithiolato), (mu-pdt)[Fe(CO)(2)(DAPTA)](2) (2) and (mu-pdt)[Fe(CO)(2)(PTA)][Fe(CO)(2)(DAPTA)] (3), were prepared and spectroscopically characterized. The water solubility of DAPTA-coordinate complexes 1-3 is better than that of the PTA-coordinate analogues. With complexes 1-3 as electrocatalysts, the overvoltage is reduced by 460-770 mV for proton reduction from acetic acid at low concentration in CH(3)CN. Significant decrease, up to 420 mV, in reduction potential for the Fe(I)Fe(I) to Fe(I)Fe(0) process and the curve-crossing phenomenon are observed in cyclic voltammograms of 2 and 3 in CH(3)CN/H(2)O mixtures. The introduction of the DAPTA ligand to the diiron dithiolate model complexes indeed makes the water solubility of 2 and 3 sufficient for electrochemical studies in pure water, which show that the proton reduction from acetic acid in pure water is electrochemically catalyzed by 2 and 3 at ca. -1.3 V vs. NHE. (c) 2006 Elsevier B.V. All rights reserved.