Synthesis, structural, and DFT studies of Cu(II) dithiocarbamate complexes

An experimental and quantum chemical study on the structures of Cu(II) dithiocarbamate complexes, from N-butyl-N-phenyldithiocarbamate ([Cu(L1)2]) and N-ethyl-N-ethanoldithiocarbamate ([Cu(L2)2]) has been performed to elucidate the geometric features in different media, starting with the crystal structure, then in polar and non-polar solvents that simulate the environment within a biological system. Crystallographic and spectroscopic techniques have been utilized for the experimental investigations to characterize the structure in the crystal form while the density functional method has been employed, along with the GGA-PBE+U scheme to carry out the theoretical investigation. DFT calculations showed that the two copper complexes were semiconductors with indirect bandgap. The calculated band gap energies were 0.821 eV and 0.879 eV for [Cu(L1)2] and [Cu(L2)2] respectively. The partial density of states showed that [Cu(L2)2] was more stable than [Cu(L1)2] due to the s-states of the oxygen. The dielectric function showed the presence of seven electronic transitions in [Cu(L1)2] and six in [Cu(L2)2] where the first three are between the upper valence band and the conduction band. The calculated absorption spectrum predicted an absorption from the infrared to UV region with a maximum of 105 cm−1. The maximum values of the reflectivity obtained are equal to 18%, for [Cu(L1)2] along the [100] direction and 14% for [Cu(L2)2] complex along the [010] direction.