Magnetic properties of two coordination isomeric cobalt(II) single-ion magnets.

Two isomeric Co(II) complexes with the same general molecular formula of [Co(napy)(NO)] (napy = 1,8-naphthyridine) have been synthesized. X-ray single crystal structural determination demonstrates that the two compounds exhibit highly irregular six- (1) and seven-coordinate (2) geometries, respectively. The magnetic measurements, X-band EPR data and theoretical calculations were thoroughly investigated. Both complexes show field-induced slow magnetic relaxation, of which the slow magnetic relaxation in 2 is attributed to an easy-plane anisotropy.