Synthesis, crystal structure, Cu2+ doped EPR and voltammetric studies of bis[N-(2-hydroxyethyl)ethylenediamine]zinc(II) squarate monohydrate

Crystal structure of [Zn(hydet-en)2]·C4O4·H2O (ZHES) (hydet-en is N-(2-hydroxyethyl)ethylenediamine) complex has been synthesized and characterized by analytical, spectroscopic (IR, UV/Vis) and voltammetric techniques. After doping Cu2+ ion, its magnetic environment has been identified by electron paramagnetic resonance (EPR) technique. The title complex crystalizes in monoclinic system with space group P21/c and with Z=4. Each hydet-en ligand acts as a tridentate ligand through the two N atoms and the hydroxyl O atom, resulting in a six coordinate Zn(II) ion. The EPR spectra were recorded in three perpendicular planes of Cu2+ doped ZHES single crystal. The calculated g and A values indicated that the paramagnetic center is rhombic symmetry with the Cu2+ ion having distorted octahedral environment. The molecular orbital bond coefficients of the Cu(II) ion in d9 state is also calculated by using EPR and optical absorption parameters. The dianion SQ2− is oxidized reversibly in two consecutive steps to the corresponding radical monoanion and neutral form.