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

Abstract

3,5-Bis(aminomethyl)pyrazole (Hbampz) forms binuclear copper(II) complexes of the formula [Cu₂(bampz)₂X₂] (X = CI, Br). The crystal structure of [Cu₂(bampz)₂Br₂] has been determined by the X-ray method: formula = CuBrN₄C₅H₉, monoclinic, space group P2₁/n, a = 9.214(1), b = 10.078(1), c = 8.775(1) Å, β = 97.33(1)°, V = 808.1 ų. Two bampz⁻ molecules combine with two copper(II) ions via the pyrazolate nitrogen and aminonitrogen atoms in the side chains affording an essentially planar N₄ 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 =—2JŜ₁.Ŝ₂) was estimated at—200.8 and—192.0 cm⁻¹ for [Cu₂(bampz)₂Cl₂] and [Cu₂(bampz)₂Br₂], respectively.

Key Words:

• Binuclear copper(II)
• pyrazolate bridge
• X-ray structure
• magnetism
• spin coupling