Hydrothermal syntheses, crystal structures and magnetic properties of two copper(II) complexes involved in situ ligand synthesis

摘要

The hydrothermal reaction of Cu(NO3)(2), isophthalate (ip) and 2,2'-bipyridine (2,2'-bpy) without or with K2Cr2O7 affords different complexes, whose structures are controlled only by the addition of the K2Cr2O7. The reaction of Cu(NO3)(2), isophthalate and 2,2'-bipyridine yields a novel one-dimensional double-chain coordination polymer [Cu-3(ip)(2)(Hipa)(2)(bpy)(2)](n) (1). However, with the addition of K2Cr2O7 in the above reaction at the same hydrothermal conditions, a discrete hexanuclear Cu(II) complex [Cu-6( ipO)(4)(2,2'-bpy)(4)(H2O)(2)]center dot 6H(2)O (2) ( ipOH= 2-hydroxyisophthalate) was isolated. It is interesting to find that the in situ reaction of isophthalate (ip) oxidized to 2-hydroxyisophthalate (ipOH) occurs. K2Cr2O7 acts as an oxidant. The magnetic properties of 1 and 2 have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the results reveal that intramolecular ferromagnetic interactions exist with weak intermolecular antiferromagnetic interactions at very low temperature in 1 and weak antiferromagnetic interactions admixture with strong ferromagnetic interactions in 2.