Magnetic interactions in hydrogen-bonded networks of hydroxymethyl-substituted phenyl nitronyl nitroxides

The ortho-, meta-, and pora-Hydroxymethyl-substituted 4,4,5,5-tetramethyl-3 -oxyl-2-phenylimidazoline 1-oxides (1-3) were synthesized and characterized by X-ray crystallography. The magnetic susceptibility was determined by te mperature-dependent SQUID measurements. The nitronyl nitroxides 1 and 3 dis play a paramagnetic susceptibility which follows the Curie-Weiss law. Weak ferromagnetic interactions can be recognized at very low temperature. The n itronyl nitroxide 2 shows temperature-dependent antiferromagnetic behavior, which can be fitted perfectly with the Heisenberg linear-chain theory with an intrachain exchange interaction of -18.43 cm(-1).