Synthesis, molecular structure, and spectroelectrochemistry of a nitrosyl iron porphyrin containing an unsymmetrical xanthene-linked porphyrin core

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• 作者：Nan Xu ; Douglas R. Powell ; George B. Richter-Addo ; ^{grichteraddo@ou.edu" class="auth_mail}
• 关键词：Iron ; Nitric oxide ; Porphyrin ; X-ray ; Redox
• 刊名：Nitric Oxide
• 出版年：15 February, 2014
• 年：2014
• 卷：37
• 期：Complete
• 页码：61-65
• 全文大小：596 K

文摘

Synthetic nitrosyl porphyrins with meso-aryl substituents are potential models for the biologically-important NO-bound P460 heme cofactor. A five-coordinate iron nitrosyl tetraaryl-porphyrin (HTPPX-CO₂H)Fe(NO) containing a xanthene-based meso substituent has been prepared. The crystal structure of this formally {FeNO}⁷ complex reveals an ordered axial and bent NO ligand (鈭燜eNO = 142.5(6) 脜) displaying an off-axis tilt of the nitrosyl N atom from the heme normal by 9.2掳. Surprisingly, the porphyrin core does not display the expected asymmetry in Feript>ript>N(por) distances frequently observed in iron nitrosyl porphyrins. The redox behavior as determined by cyclic voltammetry reveals, in contrast to most (por)Fe(NO) compounds, a fast NO dissociation after electrooxidation in CH₂Cl₂ to result in a net chemically-irreversible oxidation at E_pa = +0.77 V vs Ag/AgCl. IR spectroelectrochemistry reveals a recombination, on the spectroelectrochemistry time-scale, of the dissociated NO on oxidation with electrogenerated [(HTPPX-CO₂H)Fe]⁺.