MAGNETOSTRUCTURAL STUDY OF SUBSTITUTED ALPHA-NITRONYL AMINOXYL RADICALS WITH CHLORINE AND HYDROXY-GROUPS AS CRYSTALLINE DESIGN ELEMENTS

We present a new family of phenyl substituted alpha-nitronyl aminoxyl radicals which contain hydroxy-and chlorine-substituents as crystal en gineering tools. The magnetic behaviour of these radicals strongly dif fers in dimensionality and strength, showing in all cases antiferromag netic interactions. We have determined the X-ray crystal structure and analysed the crystal packings of these radicals. From this analysis a ll the observed magnetic properties can be conveniently rationalized b y only considering the close contacts of NO groups of neighbouring mol ecules according to the generally accepted mechanisms for intermolecul ar magnetic interactions. Beside the strong O-H ... O(-N) hydrogen bon ds and the weaker C-H ... O(-N)hydrogen bonds, weak Cl ... H bonds als o seem to play a significant role in determining the molecular arrange ment in the solid state and, therefore, the magnetic properties. In on ly one case are close Cl ... Cl contacts observed, pointing to attract ive interactions between chlorine atoms.