Magnetic properties of asymmetric Co(II) dimer at low temperatures

Magnetic properties of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2)center dot 3H(2)O have been studied from the magnetization data obtained in the high magnetic field-low temperature experiments (B <= 20 T, 2.2 K <= T <= 29 K). An excellent agreement between experimental and calculated data for all experimental temperatures was achieved within the framework of the isolated Ning Co(II) pairs in the ground state, where each cobalt ion from the pair was situated in a differently distorted octahedral environment ("asymmetric dimer"). The obtained values for g-factors (g(a) and g(b)), and for the intracluster exchange integral J/k(B) = (-16.0 +/- 0.5) K confirm both the previous results on the crystal structure of the complex under consideration and the assumption on the strong antiferromagnetic coupling between cobalt ions realized by the superexchange interaction over the asymmetric oxalato bridge.