Observation of Field-Induced Single-Molecule Magnet Behavior in an Octahedrally Coordinated Binuclear Co2 Compound

A binuclear cobalt compound, namely, [Co2(L)2Cl2(H2O)4].2Cl.2H2O (1), was synthesized by acylhydrazone Schiff base ligand N3-(4-pyridyl)-4-hydroxybenzoylhydrazone (HL) and CoCl2.6H2O. The crystal structure study suggests that each CoII ion in 1 is surrounded by two nitrogen atoms and one oxygen atom from ligand, one chloride ion and two oxygen atoms from two water molecules, giving rise to six-coordinated geometry, where two N atoms from two ligands as bridges link two CoII ions. The direct-current (dc) magnetic susceptibility measurements reveal the existence of antiferromagnetic coupling interaction in 1. The alternating-current (ac) magnetic susceptibility measurements indicate that 1 exhibits field-induced slow magnetic relaxation behavior with energy barrier (Ueff) of 51.80 K, standing out among Co2-SMMs. This study demonstrates that the large magnetic anisotropy of each CoII ion and the weak antiferromagnetic coupling interaction between two CoII ions can improve Co2-SMMs performance effectively.