1,10-Phenanthroline-dithiolate mixed ligand transition metal complexes. Synthesis, characterization and EPR spectroscopy

A series of new N2S2 mixed ligand transition metal complexes, where N2 is phenanthroline and S2 is 1,2-dithiooxalate (dto) or 1,2-dithiosquarate (dtsq), has been synthesized and characterized. IR spectra reveal that the 1,2-dithiolate ligands are coordinated via the sulfur atoms forming a N2S2 coordination sphere. The copper(II) complex [Cu(phen)(dto)] was studied by EPR spectroscopy as a diamagnetically diluted powder. The diamagnetic dilution resulted from doping of the copper complex into the isostructural host lattice of the nickel complex [Ni(phen)(dto)]. The electronic situation in the frontier orbitals of the copper complex calculated from the experimental data is compared to the results of EHT and DFT calculations. Furthermore, one side product, chlorobis(1,10-phenanthroline)copper(I) ethanol solvate hydrate [(phen)2CuCl]·C2H5OH·H2O, was formed by a reduction process and characterized by X-ray diffraction. In the crystal packing one-dimensional columns of dimers are formed, stabilized by significant π–π interactions.