Synthesis, structure, UV–Vis–IR spectra, magnetism and theoretical studies on CuII[(2-aminomethyl)pyridine](thiocyanate)2 and comparisons with an analogous CuII complex

Abstract: The title complex was synthesized under self-assembly conditions using Cu(acetate)2·H2O, 2-amp (=2-aminomethylpyridine) and KSCN, and was characterized by IR, elemental analysis and single crystal structural analysis, and its spectral and RT magnetic properties were investigated. The asymmetric unit consists of a square planar Cu(II) center, with two ligand N atoms and two anionic Ns forming the square plane. In the unit cell, the monomeric complex assembles into 2-D layers through very weak non-bonded interactions between anionic S and Cu2+. Further, the structure was satisfactorily modeled by calculations based on Density Functional Theory (DFT), and the UV–Vis and IR spectra are analyzed in depth with the help of Time Dependent DFT (TDDFT). The results indicate that the absorption maxima are at relatively high energy and are mainly assigned to π→π∗ transitions (in pyridine), with a fair contribution of metal to ligand charge transfer (MLCT) and ligand to ligand charge transfer (LLCT) transitions. All the low lying transitions are categorized as mixed MLCT/LLCT. A very weak but broad band in the higher wavelength region has been detected and identified as a d–d transition band. Also, it has been found that when the ligand ratio is modified, the formation of Cu(2-amp)2(SCN)2 takes place under the same self-assembly conditions, whose structure only has been recently reported. Structural, spectral and theoretical comparisons are presented for both complexes. [Copyright &y& Elsevier]