Synthesis, Characterization and Thermodynamic Study of the Solid State Coordination Compound Ni(Nic)2•H2O(s) (Nic=Nicotinate)

A novel compound-monohydrated nickel nicotinate was synthesized by the method of room temperature solid phase synthesis and ball grinder. FTIR, chemical and elemental analysis, TG/DTG, and X-ray powder diffraction technique were applied to characterize the structure and composition of the coordination compound. Low-temperature heat capacities of the solid coordination compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 386 K. A solid-solid phase transition occurred in the temperature range of 328-358 K in the heat capacity curve, and the peak temperature, the molar enthalpy and molar entropy of the phase transition were determined to be T-trs = (356.759 +/- 0.697) K, Delta H-trs(m) = (13.650 0.408) kJ.mol(-1), and Delta S-trs(m) = (38.279 +/- 0.086) J.K-1.mol(-1), respectively. The experimental values of the molar heat capacities in the temperature ranges of 78-328 K and 358-386 K were fitted to two polynomials, respectively. The polynomial fitted values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at the intervals of 5 K.