A HINDERED ROTATION OF THE SUBSTITUENTS IN SOME PHENOXYL RADICAL AS STUDIED BY ENDOR

The ENDOR spectrum of bis-(3,5-di-t-butyl phenoxyl)-methyl was observed from −80°C to −20°C. The hyperfine coupling constants of both the ring and the t-butyl protons were precisely measured, and the saturation behavior of these ENDOR absorption was investigated. The temperature dependence of the hyperfine coupling constants was studied and the evidences of a restricted rotation of both phenoxyl and t-butyl groups were demonstrated in this radical.