CRYSTAL-STRUCTURES OF TEMPO RADICALS SHOWING FERROMAGNETIC INTERACTION

Some of the 4-arylmethyleneamino-TEMPO (2,2,6,6-tetramethyl-piperidin- 1-oxyl) radical crystals showed an intermolecular ferromagnetic intera ction. The X-ray structure analyses were performed on 4-arylmethylenea mino-TEMPO crystals (aryl = phenyl, p-chlorophenyl, p-biphenyl, p-phen oxyphenyl, p-bromophenyl, 3,5-dichlorophenyl, 3-pyridyl, naphthyl and p-fluorophenyl) at room temperature to investigate whether any systema tic intermolecular interactions were demonstrated among these crystals . No special interactions except van der Waals interaction were observ ed in these crystals. As for the arrangements of N-O radicals in the c rystals, two-dimensional O ... O networks are constructed, of which fo rms are various. A sheet-like arrangement of the N-O radicals is consi dered to be essentially important for the magnetic interactions, altho ugh the O ... O distances are long for the direct interaction between radicals.