Preparation, crystallography and spectroscopic properties of the polymeric {(1-(E)-2-pyridinylmethylidene)semicarbazone)(aqua)copper(II)} sulphate dihydrate complex: Evidence of dynamic Jahn-Teller effect

Pyridine-2-carbaldehyde semicarbazone ligand (HL) reacts with copper(II) sulphate in water solution to yield the coordination polymer [{CuII(HL)(H2O)(SO4)}n] (1). The crystals are triclinic with space group P(−1) and the metal ion is occupying a distorted octahedral geometry. EPR results show that a dynamic Jahn-Teller (J-T) effect is operative in water solutions and also support the stability of the polymeric chains as they continue to show a characteristic half-field ΔmS = ±2 transitions. UV-visible spectrum analysis allowed access to the J-T stabilization energy of 5995 cm−1 in water. Thermogravimetric/differential thermal analysis curves showed a step-by-step decomposition of complex 1 with loss of water, release of SO3 and oxidation of the semicarbazone ligand in the 30-422 °C range.