Low-temperature heat capacities and standard molar enthalpy of formation of the solid-state coordination compound trans-Cu(Ala)2(s) (Ala = l-α-alanine)

Low-temperature heat capacities of the solid coordination compound trans-Cu(Ala)2(s) have been measured by a precision automated adiabatic calorimeter over the temperature range from T = 78 K to 390 K. The experimental values of the molar heat capacities in the temperature region were fitted to a polynomial equation of heat capacities (Cp,m) with the reduced temperatures (X), [X = f (T)], by a least square method. The smoothed molar heat capacities and thermodynamic functions of the complex trans-Cu(Ala)2(s) were calculated based on the fitted polynomial. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were tabulated with an interval of 5 K. Enthalpies of dissolution of {Cu(Ac)2·H2O(s) + 2Ala (s)} and 2:1 HAc (aq) in 100 ml of 2 mol dm−3 HCl, respectively, and trans-Cu(Ala)2(s) in the solvent [2:1 HAc (aq) + 2 mol dm−3 HCl] at T = 298.15 K were determined to be image, image, and image by means of an isoperibol solution-reaction calorimeter. The standard molar enthalpy of formation of the compound was determined as image from the enthalpies of dissolution and other auxiliary thermodynamic data using a Hess thermochemical cycle.