Preparation, Crystal Structure and Thermal Decomposition Mechanisms of [Ni(CHZ)₃](TNR) · 5H₂O

The compound [Ni(CHZ)₃](TNR) · 5H₂O was prepared by using nickel carbonate, the aqueous solution of styphnic acid and carbohydrazide as reagents. The crystal structure of [Ni(CHZ)₃] (TNR) · 5H₂O was determined by using single crystal diffraction analysis. Thermal decomposition mechanisms of the compound were studied by using TG-DTG, DSC and IR techniques. The crystalline was in triclinic system with space group P1. The unit cell parameters are as follows: a = 1.045 40(10) nm, b = 1.167 1(2) nm, c = 1.227 8(2) nm, α = 109.190(10)°, β = 121.168(12)°, γ = 99.700(10)°, V = 1.261 3(3) nm³, Z = 2, D_c = 1.744 g/cm³, μ(Mo, Kα) = 0.873 mm^-1, F(000) = 688, R = 0.041 9, R_w = 0.105 3. Carbohydrazide served as a bidentate, coordinating to nickel cation with its carbonyl oxygen atom and the first nitrogen atom so that a five-membered chelating ring is formed. There are three such rings in the molecule. The coordination number is six and its configuration is deformed octahedral. The decomposition mechanisms confirm that the first dehydration process lost four water molecules, and the second step dehydrate one molecule. The residue is Ni₂O₃ at 500°C, finally.