Kinetics of binding of O2 and CO to 'double-sided' porphyrinatoiron(II) complexes

Teruyuki Komatsu, Etsuo Hasegawa, Shin Ichi Kumamoto, Hiroyuki Nishide, Eishun Tsuchida

研究成果: Article査読

11 被引用数 (Scopus)

抄録

The kinetics of binding of O2 and CO to double-sided porphyrinatoiron(II) complexes having ester pockets on both sides of the porphyrin plane has been studied. The specific environment created by the four ester groups around the central iron(II) ion of 5,10,15,20-tetrakis(2,6-di-tert-butylacetoxyphenyl)porphyrinatoiron(II) 2 results in binding which is not affected by solvation. The lower binding affinity for CO of 5,10,15,20-tetrakis(2,6-dipivaloyloxyphenyl)porphyrinatoiron(II) 1 compared to that of 5,10,15,20-tetra (o-pivalamidophenyl)porphyrinatoiron(II) is attributed to the unfavourable steric repulsions between the axial imidazole ligand and the pivaloyloxy groups, and is reflected in decreased association and increased dissociation rates. On the other hand, axial base ligation to 2 is not inhibited by the tert-butylacetoxy groups. Therefore, the lower binding affinity for O2 exhibited by 2 compared to that of an amide fenced porphyrin complex is ascribed to the loss of local polarity in the cavity. The less-polar ester groups of the double-sided porphyrinatoiron complex result in an increased rate of dissociation of O2. The activation energy for gaseous ligand association to complex 2 was determined.

本文言語English
ページ(範囲)3281-3284
ページ数4
ジャーナルJournal of the Chemical Society, Dalton Transactions
12
DOI
出版ステータスPublished - 1991

ASJC Scopus subject areas

  • 化学 (全般)

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