Synthesis, structure, spectroscopic and electrochemical properties of bis(histamine-saccharinate) copper(II) complex

Crystal structure of [Cu(hsm)2(sac)2] (hsm is histamine and sac is saccharinate) complex has been determined by X-ray diffraction analyses and its magnetic environment has been identified by electron paramagnetic resonance (EPR) technique. The title complex crystallizes in the monoclinic system, space group P 21/c with a = 7.4282(4), b = 22.5034(16), c = 8.3300(5) Å, β = 106.227(4)°, V = 1336.98(14) Å3, and Z = 2. The structure consist of discrete [Cu(hsm)2(sac)2] molecules in which the copper ion is centrosymmetrically coordinated by two histamine ligands forming an equatorial plane [Cu–Nhsm = 2.024(2) and Cu–Nhsm = 2.0338(18) Å]. Two N atoms from the saccharinate ligands coordinate on the elongated axial positions with Cu–Nsac being 2.609(5) Å. The complex is also characterized by spectroscopic (IR, UV/Vis) and thermal (TG, and TDA) methods. The cyclic voltammogram of the title complex investigated in DMSO (dimethylsulfoxide) solution exhibits only metal centred electroactivity in the potential range – 1.25–1.5 V versus Ag/AgCl reference electrode. The molecular orbital bond coefficients of Cu(II) ion in d9 state is also calculated by using EPR and optical absorption parameters.