H-1-ENDOR INVESTIGATIONS ON GAMMA-IRRADIATED BETAINE CALCIUM-CHLORIDEDIHYDRATE AT ROOM-TEMPERATURE

The ENDOR technique is applied to study the structure of the free radi cal N(CH3)(3), found in the high temperature phase in the incommensura te crystal BCCD after gamma-irradiation. The radical possesses a plana r structure with strong deviation from the C-3 symmetry. The hybridiza tion of the nitrogen atom is sp2(.) Each of the three methyl groups ex hibits a single ENDOR line, indicating the rotation of groups at room temperature. The deviation of the H-1 hyperfine tensors of the methyl groups from axial symmetry is not a hint as to a hindered rotation of the groups. This is predicted by the C-2 symmetry of the system consis ting of a pi orbital and a rotating CH3 group.