ISSN:
1573-935X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Reaction rate constants have been measured for the oxidation of cholesterol by atmospheric oxygen in the presence of tetra-meso-substituted metalloporphyrins [MP] (M = Ni, Cr, Mn, Fe, Co). The results have been interpreted by the use of data on the structure of metal complexes and reaction mechanisms. It has been established that the reaction proceeds at a high rate when the oxygen in the composition of the intermediate complex [MO2P] is in the singlet spin state. The singlet state of O2 is occupied in the case in wich the metal ion in the porphyrin complex is in a high-spin state. The spin state and related catalytic activity of the metalloporphyrin is regulated by meso-substituents in the porphine ring. The influence of meso-substituents is predicted theoretically within the framework of a generalized orienting effect, the presence of which is supported by an analysis of 13C NMR data for meso-substituted metalloporphyrins.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00536357
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