Metall-π-komplexe von benzolderivaten : X. ESR- und 1H-NMR-spektroskopische untersuchung des elecktronenaustausches im system bis(η-aren)chrom(0)/ bis(η-aren)chrom(I)☆☆☆

Abstract The rate constants k ex for electron exchange between bis(η-arene)chromium-(0) complexes of toluene, p -xylene, mesitylene and durene and the corresponding radical cations were calculated from 1 H NMR line broadening data. Since methyl and aryl protons do not exhibit the same limiting case of pulse strength, a method suggested by Johnson for the determination of k ex which does not require the concentration of the paramagnetic exchange partner to be known, should be applicable. The parameters obtained, k ex ≈ 3 X 10 8 l mol −1 sec −1 and E a 8.6 kJ mol −1 approach values for diffusion controlled reactions. There is no significant influence of the degree of methylation on the rate of electron exchange.