Synthesis, Crystal Structure and Magnetic Properties of a (/x-Hydroxo)(jLi-Pyrazolato) Dicopper(II) Complex

Preparation and magnetic properties of a 3,5-dimethylpyrazolate bridged binuclear copper(II) complex [Qi2(L)(3 ,5-pyz)] (L = l,3-Bis(2-Hydroxy-5-Chlorosalicylideneamino)propan-2-ol) is reported. The crystal structure determined by X-ray diffraction methods. (C22H20N4O3CI2CU2), triclinic, space group PI, a = 9.622(3)hb = 10.921(2), c = 11.420(3) A, q = 100.73(2), ß = 94.04(2), 7 = 108.08(2)°, V = 1110.2(5) A3, Z = 2. Two copper(II) ions in a square-planar coordination are bridged via alkoxide oxygen and 3,5-dimethyl pyrozolate ni­ trogen atoms to form a dinuclear unit. The metal coordination sphere is four-coordinate, planar with an N2O2 donor set. The dihedral angle between the two coordination planes is 166.83°. There are significant intermolecular interactions between neighbouring binuclear entities. The shortest intermolecular Cu(l)... Cu(l)' distance is 3.383(1) A and the Cu(l) O (l)1 distance is 2.666(3) A (i = 1 -x, -y, 1 z). The variable-temperature magnetic susceptibility measurement for a powdered sample of the complex was carried out in the temperature range 5 350 K and analysed to obtain values of the parameter J in the exchange Hamiltonian H = -2JScu Scu; 2J = -164 cm-1. The magnetic moment at 300 K is about 2.42 nb, and 0.22 /ub at 5 K. The weak antiferromagnetism of the present complex is reasonably explained in terms of the orbital countercomplementary effect based on Hoffmann's theory for super-exchange interaction.