Kinetic studies of the complex formation of iron(III) with 4-isopropyltropolone by a high-pressure stopped-flow technique. Mechanistic difference between the hexaaquairon(III) ion and the pentaaquahydroxoiron(III) ion in their complexation

Koji Ishihara, Shigenobu Funahashi, Motoharu Tanaka

研究成果: Article

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The formation rate of the 1:1 iron(III) complex with 4-isopropyltropolone (Hipt) has been studied spectrophotometrically in aqueous solution of low pH at various temperatures and pressures by a stopped-flow technique. The rate law is expressed as d[Fe(ipt)2+]/dt = (k1 + k2KFeOH [H+]-1)(1 + KH [H+])-1[Fe3+][Hipt], with k1 = 21.7 ± 1.1 M-1 s-1 and k2 = (6.30 ± 0.31) × 103 M-1 s-1 at 25°C and I = 1.00 M at atmospheric pressure. The activation parameters for the reaction of Fe(OH2)6 3+ (k1 path) and the reaction of Fe(OH2)5OH2+ (k2 path) are as follows: ΔH 1 = 59.5 ± 3.0 kJ mol-1, ΔS 1 = -19.8 ± 3.0 J mol-1 K-1, ΔV 1 = -8.7 ± 0.8 cm3 mol-1; ΔH 2 = 29.2 ± 3.6 kJ mol-1, ΔS 2 = -72.3 ± 5.0 J mol-1 K-1, ΔV 2 = 4.1 ± 0.6 cm3 mol-1. Associative- and dissociative-interchange mechanisms are most probably operative for the k1 and k2 paths, respectively.

元の言語English
ページ(範囲)194-198
ページ数5
ジャーナルInorganic Chemistry
22
発行部数2
出版物ステータスPublished - 1983
外部発表Yes

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ASJC Scopus subject areas

  • Inorganic Chemistry

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