The copper salt [Cu(H2O)(2)(imH)(4)]center dot Sq has been synthesized at room temperature. Crystal structure of the [Cu(H2O)(2)(imH)(4)]center dot Sq (Sq is squarete dianion (C4O42-) and imH is imidazole (C3H4N2)) complexes has been investigated by single-crystal X-ray diffraction analyses and the environment of copper ion has been identified by EPR. The single crystal is triclinic with the space group P1. The unit cell dimensions of the crystals are a=9.317 angstrom, b=9.958 angstrom, c= 12.130 angstrom, alpha=69.99 degrees, beta=76.61 degrees and gamma=78.13 degrees. The unit cell contains two molecules. The Cu(II) atom has an octahedral arrangement in which the Cu(II) ion lies on the inversion canter and is coordinated by four imidazole ligands with the equatorial plane and two water molecules with the octahedral axial. The complex shows a normal magnetic moment and the single crystal EPR spectra consist of two sets of four hyperfine lines of copper. The ground wave function of the hole of the Cu2+ is an admixture of d(x2-y2) and d(z2) states. (c) 2006 Elsevier B.V. All rights reserved.