Synthesis, crystal structure and magnetic properties of a trinuclear Cu(II)-pyrazolate complex containing μ₃-OH

Abstract

A new pyrazolate-bridged quasi-hexacopper(II) complex [Cu₃(μ₃-OH)(μ-pz)₃(pzH)₃ (μ₃-ClO₄)]₂(μ-ClO₄)₂ · (CH₃OH)_0.33 · (C₂H₅OH)_0.66 · H₂O (pz = pyrazolate), 1, has been isolated and characterized by single crystal X-ray diffraction, elemental analysis, IR and UV–visible spectra and magnetic susceptibilities. The complex crystallizes in the orthorhombic system, space group Pbca (, No. 61), a = 17.771(4) Å, b = 16.143(4) Å, c = 25.502(6) Å, V = 7316(3) ų, Z = 8, F(000) = 3521, D _c = 1.576 g cm⁻³. The structure of 1 consists of two [Cu₃(μ₃-OH)(μ-pz)₃(pzH)₃(μ₃-ClO₄)]²⁺ trimers, which are weakly bridged by two perchlorate ions via centrosymmetric operation to form a trigonal prism with the six Cu atoms at six vertexes. Magnetic measurements were performed in the temperature range 2–300 K. The experimental data above 9 K could be satisfactorily reproduced by using an isotropic exchange model, (1), with parameters of J = −241.91 cm⁻¹, ZJ′ = −23.04 cm⁻¹ and g = 2.07, showing strong antiferromagnetic behaviors in Cu₃ unit and weak intertrimer magnetic interaction.

Keywords:

• Tricopper complex
• Crystal structure
• Antiferromagnetic behavior
• Spin frustration

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 20771084), Tianjin Natural Science Foundation (No. 06YFJMJC12700) and SRF for ROCS, SEM of China.