ESR spectroscopic investigation of some 4‐substituted 1,3,2‐dithiazolyl and 2,3,1‐dithiazolyl radicals

Further information has been obtained on the electronic structure of 1,3,2‐dithiazol‐2‐yl radicals. The structure has been well characterized previously except for positions 4 and 5 in thering. We have obtained solution and powder ESR spectra of radicals substituted with 13 C in both positions and of radicals substituted with nitrogen or phosphorus in the 4‐position. It is probably the first time that a compound has been prepared containing thering. Two especially interesting facts emerged from the ESR spectra of these 1,3,2‐dithiazolyl radicals: the 13 C‐substituted radical has a considerable amount of p spin density in the plane of the ring and the phosphorussubstituted radical has a very low unpaired spin density at the phosphorus atom. It is known that 1,3,2,4‐dithiadiazolyl radicals isomerize readily by photolysis to the symmetrical 2,3,1,4‐dithiadiazolyl radicals; we attempted the same reaction with Bu tand a new radical was produced that we have been unable to identify.