Unique aspects of the 1-methylimidazole ligation to corrphycenatoiron(III)

Saburo Neya, Yoshiki Ohgo, Mikio Nakamura, Noriaki Funasaki

研究成果: Article査読

1 被引用数 (Scopus)


The coordination behaviors of chloro corrphycenatoiron(III), a novel hemin isomer with a trapezoidal metallo core, against imidazole, 1-methylimidazole, and 2-methylimidazole were followed by spectrophotometry in chloroform at room temperature. The examined compound is chloro 12, 17-bis(ethoxycarbonyl)-2,3,6,7,11,18-hexamethylcorrphycenatoiron-(III). Titration of 2-methylimidazole and imidazole proceeded with and without accumulation of an intermediate mono imidazole species, respectively. On the other hand, a significant amount of an intermediate adduct was found to accumulate during 1-methylimidazole binding despite the absence of any steric hindrance in the iron(III)-N(1-methylimidazole) coordination bond. This is in remarkable contrast with the conventional results for porphyrinatoiron(III). The proton NMR analysis of the mono 1-methylimidazole binding to corrphycenatoiron(III) afforded a formation constant closely similar to that obtained from the visible spectra. EPR definitely assigned the iron(III) high-spin state for the intermediate. Accumulation of the mono 1-methylimidazole intermediate was explained in terms of the contracted core in corrphycene. The narrow iron cavity weakens the axial iron-chloride bond facilitating coordination of the first 1-methylimidazole. The four non-orthogonal iron(III)-N(pyrrole) bonds formed in the trapezoidal cavity further disturb the incoming motion of the iron(III) atom into corrphycene plane upon second 1-methylimidazole ligation. Accumulation of mono 1-methylimidazole intermediate was more evident in ferric corrphycenatoiron(III) with bromide and iodide, supporting the proposed changes in iron reactivity upon deformation of the equatorial coordination environment.

ジャーナルBulletin of the Chemical Society of Japan
出版ステータスPublished - 2000 12月

ASJC Scopus subject areas

  • 化学 (全般)


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