Isolation of crystals of a planar nitronyl nitroxide radical:2-phenylbenzimidazol-1-ylN,N′-dioxide(PBIDO)

A planar nitronyl nitroxide radical, 2-phenylbenzimidazol-1-ylN,N′-dioxide, has been isolated in a stable single crystal form. X-Ray analysis has shown that the radical molecules form a dimeric two-dimensional structure. The dominant magnetic interactions have been found to be antiferromagnetic. Anomalous temperature dependence of susceptibility was observed below 10 K. The EPR study indicates that this is ascribable to spin-multiplet states generated in the crystal.