Thermal behaviour of nickel(II) sulphate, nitrate and halide complexes containing ammine and ethylenediamine as ligands Kinetics and evolved gas analysis

Thermal behaviour of nickel amine complexes containing SO4 (2-), NO3 (-), Cl- and Br- as counter ions and ammonia and ethylenediamine as ligands have been investigated using simultaneous TG/DTA coupled with mass spectroscopy (TG/DTA-MS). Evolved gas analyses detected various transient intermediates during thermal decomposition. The nickel ammonium sulphate complex produces NH, N, S, O and N-2 species. The nickel ammonium nitrate complex generated fragments like N, N-2, NO, O-2, N2O, NH2 and NH. The halide complexes produce NH2, NH, N-2 and H-2 species during decomposition. The ligand ethylenediamine is fragmented as N-2/C2H4, NH3 and H-2. The residue hexaamminenickel(II) sulphate produces NiO with crystallite size 50 nm. Hexaammine and tris(ethylenediamine)nickel(II) nitrate produce NiO in the range 25.5 nm and 23 nm, respectively. The halide complexes produce nano sized metallic nickel (20 nm) as the residue. Among the complexes studied, the nitrate containing complexes undergo simultaneous oxidation and reduction.