Thermal and kinetic analysis of a new hydrazone-oxime ligand and its cadmium(II) complex: Synthesis, spectral characterization, crystallographic determination and Hirshfeld surface analysis

Abstract

A novel cadmium complex, [Cd(L)2](NO3)2(H2O)2, (hereinafter simply designated as Cd IIL2) has been syn-thesized by reacting a hydrazone-oxime ligand, (2E,3E)-3-(2-(6-chloropyridin-2-yl)hydrazono)butan-2-one oxime ( L ), with cadmium nitrate tetrahydrate. The ligand L and Cd IIL2 were characterized by LC/MS-MS, FT-IR, elemental analysis, NMR, molar conductivity, UV-Vis spectroscopy and thermal analysis. The struc-ture of the Cd IIL2 was also elucidated by the single-crystal X-ray diffraction technique. The X-ray powder diffraction pattern of Cd IIL2 was then performed to confirm the purity of the crystalline compound. Addi-tionally, as a result of analytical and spectroscopic data suggested that the metal in Cd IIL2 exhibits a dis-torted octahedral geometry. Hirshfeld surface analysis (HSA) was used in conjunction with 2D fingerprint plots to evaluate intermolecular forces, involving hydrogen bonds, in the crystal lattice of Cd IIL2. Thermal and kinetic studies of the synthesized compounds were performed between 30 and 10 0 0 degrees C using dif-ferent heating rates of 5, 10, and 15 degrees C/min under two different atmosphere (N 2 and O 2 ). The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) integral methods have been selected to determine the values of the reaction activation energies ( Ea ). According to the Ea values, FWO was selected to in-vestigate the thermodynamic parameters, i.e., the free energy change ( AG), entropy ( AS) and enthalpy (AH) changes. The ligand and its complex exhibited better thermal stability and higher thermodynamic values in O 2 atmosphere than in N 2 atmosphere. (c) 2022 Elsevier B.V. All rights reserved.