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Protophilicity, electrochemical property, and desulfurization of diiron dithiolate complexes containing a functionalized C-2 bridge with two vicinal basic sites
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2009 (English)In: Polyhedron, ISSN 0277-5387, Vol. 28, no 6, 1138-1144 p.Article in journal (Refereed) Published
Abstract [en]

Two chiron dithiolate complexes [{mu-SC(NBn)CH(NHBn)S-mu)Fe-2(CO)(5)L] (L = PPh3, 2; P(Pyr)(3), 3) containing a functionlized C-2 bridge with two vicinal basic sites were prepared and characterized as models of the FeFe-hydrogenase active site. The molecular structures of 2 and its N-protonated form [(2H(N))(OTf)] were determined by X-ray analyses of single crystals. In the solid state of [(2HN)(OTf)]. Each asymmetric unit contains a molecule of [(2H(N))(OTf)] and a molecule of water. The molecule of water is close to the iron atom of the [Fe(CO)(3)] unit (Fe center dot center dot center dot O(H2O), 4J 99 angstrom). The complexes 2 and 3 are relatively protophilic. P-31 NMR spectra and cyclic voltammograms show that they can be protonated by the mild acids CCl3COOH and CF3COOH. Electrochemical studies show that the first reduction peak of 3 at - 1.51 V versus Fc(+)/Fc is 110 mV more positive than that (-1.62V) found for the analogous diiron azadithiolate complex [{(mu-SCH2)N(CH2C6H5)}Fe-2(CO)(5)P(Pyr)(3)] (7). Protonation of 2 and 3 leads to the anodic shifts of 610-650 mV for the (FeFe1)-Fe-1/(FeFe0)-Fe-1 reduction potentials. The shifts are apparently larger than that (450 mV) for protonation of 7. The reaction of the all-carbonyl complex [{(mu-SC(NBn)CH(NHBn)S-mu}Fe-2(CO)(5)L] with two equivalents of bis(diphenylphosphino)methane (dppm) in refluxing toluene affords a desulfurized complex 1(mu-S)(mu-dppm)(2)Fe-2(CO)(4)] (6). The reaction process was studied. A dppm mono-dentate intermediate [{mu-SC(NBn)CH(NHBn)S-mu)Fe-2(CO)(5)(kappa(1)-dppm)] (4) and a dppm mu-bridging species [{mu-SC(NBn)CH(NHBn)S-mu)Fe-2(CO)(4)(mu-dppm)] (5) have been isolated and spectroscopically characterized.

Place, publisher, year, edition, pages
2009. Vol. 28, no 6, 1138-1144 p.
URN: urn:nbn:se:kth:diva-18392DOI: 10.1016/j.poly.2009.01.006ISI: 000265817700014ScopusID: 2-s2.0-63349111156OAI: diva2:336439
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-01-27Bibliographically approved

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Sun, Licheng
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Organic Chemistry
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