ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Efficiency of the Photochemical Co-C-Bond Cleavage in σ-Alkyl-Co(III)(salen)-and-Co(III)(salphen)-Complexes.The photodealkylation rate of RCoIII(chel) X complexes (R = methyl, ethyl; chel = salen, salphen; X = H2O, py, PPh3) depends on the nature of ligands and solvents as well as on the concentration of oxygen and scavengers for alkyl radicals. The rapid recombination of the fragments R. and Co(chel)X is responsible for the low quantum yields of the anaerobic dealkylation. The quantum yields may reflect the H-donating ability of the solvents used. Lewis bases X in the trans position generally cause a decrease of quantum yields relative to the pentacoordinated species RCo (chel). The anaerobic photolysis can be accelerated by the addition of scavengers for alkyl radicals (e. g. Koelsch radical, nitrosodurene, styrene). The quantum yield also increases in the presence of oxygen, preventing the recombination of the fragments of the cobalt-carbon bond scission by forming alkyl-peroxocomplexes ROOCo(chel)X.α-Hydroxyalkylradicals arising from the decomposition of the ROOCo(chel)X complexes via secondary reactions probably react with the starting σ-alkyl complexes and cause the dependence of quantum yields on the light intensity.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19823240108
