Abstract
A copper(II) complex, [Cu(Dach)(2)(H2O)]Cl-2 (1) (Dach = cis-1,2-Diaminocyclohexane) has been prepared and characterized by IR spectroscopy and X-ray crystallography. The crystal structure of complex 1 is ionic consisting of [Cu(Dach)(2)(H2O)](2+) cation and two chloride counter ions. The copper atom in the complex ion assumes a distorted square pyramidal geometry with water occupying the apical position. The adjacent molecules are joined by hydrogen bonding to form irregular chains. The structures of [Cu(Dach)(2)(H2O)]Cl-2 (1) and three of its analogues, [Cu(Dach)(2)Cl]Cl center dot H2O (2), [Cu(Dach)(2)(H2O)Cl]Cl (3) and [Cu(Dach)(2)Cl-2]center dot H2O (4) were predicted by DFT calculations. The DFT results reveal that in the gas phase, the structure 1 is less stable in comparison to the calculated structure, [Cu(Dach)2Cl2]center dot H2O (4). The additional calculations were performed for the complexes investigated in solution (water) using the polarizable continuum model. According to these calculations, the electronic energies (stabilities) of the complexes 1 and 4 in the solvent are comparable to each other. The atomic charges and second-order interaction energies between orbitals for complexes 1-4 were calculated with natural bond orbital (NBO) analysis.