Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues.

Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues. Research Abstract Details 

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Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues. Abstract Text:

Min Zhao,Datong Song,Stephen J Lippard,

Recently, we reported the synthesis of a carboxylate-rich non-heme diiron enzyme model compound [Fe2(mu-O2CAr(Tol))4(4-CNPy)2] (1), where (-)O(2)CAr(Tol) is 2,6-di-p-tolylbenzoate and 4-CNPy is 4-cyanopyridine (Yoon, S.; Lippard, S. J. J. Am. Chem. Soc. 2005, 127, 8386-8397). A metal-to-ligand charge-transfer band in the visible region of the optical absorption spectrum involving the nitrogen-donor ligand endowed this complex with a distinctive red color that facilitated analysis of its chemistry. Following this strategy, we prepared and characterized two related isomeric complexes, windmill (3) and paddlewheel (4) species having the formula [Fe2(O2CAr(Tol))4(4-AcPy)2], where 4-AcPy is 4-acetylpyridine. In anhydrous solvents, 1 and 4 adopt paddlewheel structures, but upon the addition of water, they convert to aquated forms, windmill structures having the composition [Fe2(mu-O2CAr(Tol))2(O2CAr(Tol))2(4-RPy)2(H2O)2]. This conversion is favored at low temperature and was studied by NMR spectroscopy. A kinetic analysis of the aquation reaction was undertaken by stopped-flow measurements between 198 and 223 K for both 1 and 4, which revealed a first-order dependence on both the diiron compound and water. The oxygenation rates for the water-containing complexes are much faster than those for the corresponding anhydrous complexes, being 20-fold faster for 4 and 10-fold more rapid for 1. The presence or absence of water had little effect on the activation enthalpies, suggesting that the loss of water may not be necessary prior to dioxygen binding in the transition state.

Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues. Publishing Authors By Initials

M Zhao,D Song,SJ Lippard,

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Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues. Journal Published:

PUBLICATION TYPE: Research Support, N.I.H., Extr

Journal: Inorganic chemistry

VOLUME: 45

Page Numbers: 6323-30

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ISSN: 0020-1669

DAY: 7

MONTH: Aug

YEAR: 2006

Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues. Information

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LANGUAGE: eng

NlmUniqueID: 366543

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Grant and Affiliation Information for Water induces a structural conversion and accelerates the oxygenation of carboxylate-bridged non-heme diiron enzyme synthetic analogues.

AFFILIATION: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Country: United States

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MEDLINETA: Inorg Chem

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