Room temperature and near-room temperature coordination polymer magnets

Four new vanadium-based coordination polymers that exhibit high magnetic ordering temperatures (Tc) have been synthesized. Magnetic measurements show that these polymers are soft ferrimagnets. The IR shows a reduced nitrile environment in these polymers, elemental analysis reveals that the compositions of the polymers are 2:1 acceptor to vanadium ratio. An electrochemical measurement of acceptors shows a weak correlation between Tc and the redox potentials. Change in the dihedral angle of an acceptor with the substitution in a specific position of the phenyl ring alters the magnetic ordering temperature in these polymers. Calculated electron affinity and Mullikan spin densities on acceptors, either in the neutral or in the anionic form, shows no relationship with the observed trend in Tc. These compounds are analogues to V[TCNE]2 complexes with varying degree of solvent of coordination.