SPECTRAL INVESTIGATIONS AND DFT STUDY OF MIXED THEOPHYILLINE-N,N-CHELATING LIGAND COPPER(II) COMPLEXES

Three new mixed-ligand theophylline (th) complexes, [Cu(th)(2)(dmen)(H2O)]center dot H2O center dot(1), [Cu(th)(2)(tmeda)(H2O)]center dot 0.5H(2)O (2) and [Cu(th)(2)(dpen)(H2O)]center dot 5H(2)O (3), were synthesized and investigated by means of infrared and ESR spectroscopic methods. As co-ligands the following ethylenediamine derivatives were used: N, N-dimethyl-ethylenediamine (dmen), N, N, N', N'-tetramethyl-ethylenediamine (tmeda) and meso-1,2-diphenyl-ethylenediamine (dpen). Structural parameters of the complexes were investigated by using the unrestricted Becke three-parameter hybrid exchange functional, combined with the Lee-Yang-Parr correlation functional (B3LYP) and LANL2DZ basis set for geometry optimizations. Complexes 1-3 adopt square pyramidal geometries.