Tailoring magnetic interactions of organic solids: Modification of triphenylverdazyl

The synthesis of the free radicals 1‐(4'‐bromophenyl)‐3,5‐diphenyl‐verdazyl (Br‐TPV), 1‐(4'‐isopropyl‐phenyl)‐3,5‐diphenyl‐verdazyl (IP‐TPV), 1,3,5,6‐tetraphenyl‐verdazyl (Ph‐TPV), 6‐(1′‐naphthyl)‐1,3,5‐tri‐phenyl‐verdazyl (1N‐TPV), 6‐(2′‐naphthyl)‐1,3,5‐triphenyl‐verdazyl (2N‐TPV), 6‐(4′‐bromophenyl)‐1,3,5‐triphenyl‐verdazyl (BrPh‐TPV) and 1,3,5,6,6‐pentaphenyl‐verdazyl (PhPh‐TPV) is described. Their magnetic properties (static magnetic susceptibility, ESR) are reported for crystalline samples. They are compared with those of 1,3,5‐triphenyl‐verdazyl (TPV) which behaves as a quasi‐onedimensional antiferromagnet in the crystalline form. Exchange interaction is increased by a factor larger than 3 compared with TPV by the introduction of the additional ring in Ph‐TPV. For Ph‐TPV and PhPh‐TPV also the crystal structure was derived by X‐ray analysis. These results are discussed with special emphasis on their meaning for the tailoring of magnetic interactions in organic solids.