Magnetism of dinuclear benzoato cobalt(II) complexes modeled by a general bilinear exchange

Combination of the cobalt(II) benzoate with N-heterocyclic ligands L-pyridine, 4-methylpyridine, iso-quinoline, furo[3,2-c]pyridine, 2-methylfuro[3,2-c]pyridine and 2,3-dimethylfuro[3,2-c]pyridine resulted in dinuclear complexes containing two benzoato bridging ligands (bz) and one aqua ligand of the composition [(μ2-H2O)(μ2-bz)2{Co(bz)(L)2}2]·Sol. The cobalt(II) centers show a weak exchange interaction of an antiferromagnetic nature. The problem of non-collinear orientation of the local D-tensors is solved by a numerical procedure considering a general bilinear exchange. The susceptibility and magnetization data were fitted by a joint functional allowing to determine the single-ion zero-field splitting that adopts large values: D/hc of the order of 50–100 cm−1.