EPR and ENDOR study of thermally produced triphenylmethyl radicals

The ENDOR spectrum of the triphenylmethyl radical formed by heat treatment of triphenylmethane has been measured in solution at 131°C. The derived hyperfine coupling constants of 2.770, 2.556 and 1.138 G were used to simulate the extremely well resolved EPR spectrum. These coupling constants are in good agreement with spin densities determined for the planar radical by the McLachlan method.