Cobalt(II) and nickel(II) cubane {M4O4} complexes derivedfrom di-2-pyridyl ketone and benzoate : syntheses, structure and magnetic properties

Abstract

Two tetranuclear complexes were obtained by a self-assembly process employing di-2-pyridyl ketone ((py)2CO), benzoate and M(NO3)2 (M = Co and Ni). The compounds [M4{(py)2C(OH)O}4(O2CPh)4], where {(py)2C(OH)O}− is the monoanion of the gem-diol form of (py)2CO, were characterized through single-crystal X-ray diffraction and magnetic measurements. Structural analysis revealed that both complexes possess a [M4O4] cubane-like core. A two-J model and magnetic anisotropy were employed to analyze the magnetic properties of both compounds. These studies indicate the presence of dominant ferromagnetic interactions within both tetranuclear cores. DFT and CASSCF/NEVPT2 calculations were also performed to support the fitting of experimental magnetic data.