Kinetics of The Reaction of Amine Complexes of Cobalt(II) Protoporphyrin IX Dimethyl Ester with Oxygen. Evidence for Hydrogen Bonding with Coordinated Oxygen

Dennis V. Stynes, Brian R. James, H. Cleary Stynes, James A. Ibers

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102 Scopus citations

Abstract

The kinetics are reported for reaction of amine complexes of cobalt(II) protoporphyrin IX dimethyl ester with oxygen in toluene to give products believed to be peroxo-bridged complexes. The reaction is first order in cobalt and oxygen and goes from first to zero order in amine (L) with increasing amine concentration. The determined rate law is consistent with the rate-determining step involving a unimolecular distortion of a 1:1 cobaltoxygen complex. Anomalously rapid rates for L = imidazole and benzimidazole are tentatively explained in terms of hydrogen-bonding effects involving the acidic proton on the imidazole ring. Similarities with hemoglobin and myoglobin are discussed. Thermodynamic data for 1:1 oxygen complexes are presented and discussed in terms of the rate law.

Original languageEnglish (US)
Pages (from-to)1142-1149
Number of pages8
JournalJournal of the American Chemical Society
Volume95
Issue number4
DOIs
StatePublished - Feb 1 1973

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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