Reversible Binding of Nitric Oxide and Carbon−Carbon Bond Formation in a Meso-hydroxylated Heme

Rath, Sankar Prasad ; Koerner, Richard ; Olmstead, Marilyn M. ; Balch, Alan L. (2003) Reversible Binding of Nitric Oxide and Carbon−Carbon Bond Formation in a Meso-hydroxylated Heme Journal of the American Chemical Society, 125 (39). pp. 11798-11799. ISSN 0002-7863

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Official URL: http://doi.org/10.1021/ja035032b

Related URL: http://dx.doi.org/10.1021/ja035032b

Abstract

Exposure of a pyridine solution of (py)2Fe(OEPO) (1) (OEPO is the trianion of octaethyloxophlorin, py is pyridine) at 22 degrees C to nitric oxide under the strict exclusion of dioxygen results in a color change from green to red-brown and the formation of {(py)(ON)Fe(OEPO)}2 (2). Monitoring the reaction by 1H NMR spectroscopy shows that the reaction is reversible. The air-sensitive product {(py)(ON)Fe(OEPO)}2 has been isolated and characterized by X-ray crystallography. NO binding is accompanied by association of two hemes through the formation of a new C-C bond between two meso carbon atoms on the porphyrin periphery. The macrocyclic ligand has a ruffled distortion that positions the C5-O1 group with its short C=O bond distance (1.237(3) A) in close proximity to the NO ligand. Since further attack upon 1 by O2 during heme degradation involves reaction in the vicinity of the oxygenated meso position, the positioning of the NO ligand so that the O2...C5 distance is only 3.100(3) A presents a highly suggestive model for the next stage of attack upon the heme periphery.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:120941
Deposited On:07 Jul 2021 13:04
Last Modified:07 Jul 2021 13:04

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