The preparation and characterization of dichlorobispyridinecopper(II) complex and its intermediates

Abstract

The dichlorobispyridinecopper(II) complex, [CuPy2Cl2], and its decomposition intermediates were synthesized and characterized by MALDI-TOF MS, far-IR, reflectance UV, atomic absorption spectroscopy techniques. The thermal decomposition reactions of the [CuPy2Cl2] were investigated by differential thermal analysis (DTA)/thermogravimetry (TG) combined system. The intermediates and the final products were analyzed by high-temperature X-ray powder diffraction (HT-XRD) technique. The XRD pattern of the complex indexed as [CuPy2Cl2] (PDF: 00-014-991) has a monoclinic crystal system, P21/n (14) space group with a = 16.9673 A, b = 8.5596 A, c = 3.8479 A; α = γ = 90.00°, β = 91.98°, V = 558.51 A3 and Z = 2.00. After comparison of thermogravimetric results of the [CuPy2Cl2], the decomposition mechanism was suggested. The intermediates were prepared separately at 217 and 245 °C temperatures which were chosen from TG curve by using a tube furnace under N2 atmosphere and characterized. The spectroscopic results reveal that the structure of the intermediates to be [CuPyCl2] and [CuPy2/3Cl2] formulas (hereafter abbreviated as 2 and 3, respectively). MALDI-TOF MS spectra of the 2 and 3 show [M+H]+ (m/z = 214.978) and [M−H]+ (m/z = 185.614), [M+C2H3O]+ (m/z = 221.002) molecular ion peaks which correspond to suggested structure for 2 and 3, respectively. Also, HT-XRD results revealed that the 2 and 3 are new phases and there is no any certain information of these phases in the literature. The values of the activation energy, E a, were calculated by model-free (Kissenger–Akahira–Sunose, Flyn–Wall–Ozawa) methods for all decomposition stages.