Antiferromagnetic Coupling in a (μ-Hydroxo)(μ-pyrazolato)dicopper(II) Complex. Synthesis, Crystal Structure, Magnetic Properties, and Theoretical Studies

Preparation, crystal structure and magnetic properties of a 3,5-dimethylpyrazolate bridged binuclear copper(II) complex [Cu2(L1)(3,5 prz)] (L1 = 1,3-Bis(2-hydroxy-1-napthylidene-amino)propan-2-ol) (1) are reported. Variable-temperature magnetic susceptibility measurements for a powdered sample of the complex were carried out in the temperature range 5 -350 K and analysed to obtain values of the parameter J in the exchange Hamiltonian H = -2JS1·S2. In the dicopper(II) complex [Cu2(L2)(3,5 prz)], (L2 = 1,3-Bis(2-hydroxy-5-chloro-salicylideneamino)propan-2-ol) (2) reported recently the antiferromagnetic interaction is much less than that of 1 (-2J = 440 cm-1), as result which is difficult to explain in terms of structural factors on the basis of widely accepted criteria. The differences in the magnetic behaviour now have been rationalized using the ligand orbital complementary concept.