Synthesis and Thermal Decomposition Kinetics of Uranium(VI) Complex with Unsymmetrical Schiff Base Ligand

Abstract

AbstractA new unsymmetrical tetradentate Schiff base ligand N‐(5‐chloro‐2‐hydroxy‐α‐phenylbenzylidene)‐N′‐(2‐hydroxy‐3‐methoxybenzylidene)‐o‐phenylenediamine (H2L) was synthesized using 5‐chloro‐2‐hydroxybenzophenone, o‐phenylenediamine and o‐vanillin. A solid UO2(II) complex of this ligand [UO2(HL)(NO3)(H2O)]·H2O was prepared and characterized by elemental analyses, IR, UV, 1H NMR spectra and molar conductance. The thermal decomposition kinetics of the complex for the third stage was studied under a non‐isothermal condition by TG and DTG methods. The kinetic equation may be expressed as: dα/dt=A·e−E/RT·3/2[(1−α)−1/3−1]−1. The kinetic parameters (E, A), activation entropy ΔS≠ and activation free‐energy ΔG≠ were also gained: E=69.08 kJ/mol, ln A=20.63, r=0.9867, ΔS≠= −79.84 J·mol−1·K−1 and ΔG≠=120.6 kJ/mol.