A pyrazolate-bridged cyclic tetranuclear copper(II) complex : synthesis, crystal structure and magnetic properties

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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  • Degang Fu
  • Feng Ji
  • Guoxiong Wang
  • Kaibe Yu
  • Tianyang Yao


Original languageEnglish
Pages (from-to)3799-3803
Journal / PublicationJournal of the Chemical Society - Dalton Transactions
Issue number19
Online published1 Jan 1996
Publication statusPublished - 7 Oct 1996
Externally publishedYes


A new pyrazolate-bridged tetranuclear copper(II) complex [{CuL(H2O)}4]·12H2O (H2L = 5-methoxycarbonylpyrazole-3-carboxylic acid) was synthesized and its crystal structure determined. The molecule has C2 symmetry and consists of four copper atoms bridged by four planar L ligands through the nitrogen atoms of the pyrazole groups to form a (-Cu-N-N-)4 12-membered ring. The co-ordination of each copper is distorted square planar. The basal plane of each copper atom is nearly parallel to a neighbouring pyrazole plane and perpendicular to another neighbouring pyrazole plane. In the crystal there is a hydrogen-bond network between water molecules and carboxylate groups which may control the packing. The magnetic properties of the complex have also been investigated down to 5 K. The fitting of the experimental data using a Heisenberg Hamiltonian shows that the exchange interaction between the copper atoms propagated through the monopyrazolate bridge is antiferromagnetic with J = -12.34 cm-1. The reason for this small value relative to those in di-μ-pyrazolato-dicopper(II) complexes is discussed.

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