Synthesis, Structure, and Magnetic Properties of Di-μ-Pyrazolatodicopper(II) Complexes of 3,5-Bis(Aminomethyl)Pyrazole

3,5-Bis(aminomethyl)pyrazole (Hbampz) forms binuclear copper(II) complexes of the formula [Cu 2 (bampz) 2 X 2 ] (X = CI, Br). The crystal structure of [Cu 2 (bampz) 2 Br 2 ] has been determined by the X-ray method: formula = CuBrN 4 C 5 H 9 , monoclinic, space group P2 1 /n, a = 9.214(1), b = 10.078(1), c = 8.775(1) Å, β = 97.33(1)°, V = 808.1 Å 3 . Two bampz − molecules combine with two copper(II) ions via the pyrazolate nitrogen and aminonitrogen atoms in the side chains affording an essentially planar N 4 environment for each metal ion. The Cu-Cu separation is 3.947(5)A. The axial site of each copper is weakly coordinated by a bromide ion with a Cu-Br distance of 2.895(4) A. Cryomagnetic investigations over the temperature range 80-300 K revealed a significant antiferromagnetic interaction through the pyrazolate bridges. The exchange integrals (J) based on the Heisenberg model (H =-2JŜ 1 .Ŝ 2 ) was estimated at-200.8 and-192.0 cm −1 for [Cu 2 (bampz) 2 Cl 2 ] and [Cu 2 (bampz) 2 Br 2 ], respectively.