Solvation energies of ferrous ion in methanol at various temperatures

The accurate determination of the solvation free energies or solvation enthalpies of ferrous ion in a given medium is subject to the determination of the most favored structures of the ferrous ion in this medium. In this work, we investigated structures, relative stabilities, clustering energies, binding energies, solvation enthalpies and solvation free energies of the ferrous ion in methanol for temperatures ranging from 20 K to 400 K. It is pointed out that the coordination number of the solvated ferrous ion in methanol is six, but could decrease slightly when the temperature increases. The temperature dependence of the relative stability of different isomers obtained proves that, for T ranging from 20 K to 400 K, the population is dominated by one structure and we noted the presence of fourfold coordinated structures for n >6. Solvation energies of ferrous ion in methanol were computed following an hybrid solvation scheme. Finally, the solvation free energy of ferrous ion in methanol at room temperature (298.15 K), is -2066.1 kJ mol(-1) and the corresponding solvation enthalpy is -2103.5 kJ mol(-1). Taking into account the temperature effects, the solvation free energies are more affected by the change of temperature mainly for temperature higher than 200 K. However, the effect of temperature is insignificant on the solvation enthalpies. At the saturation, the binding electronic energy per methanol molecule, the binding enthalpy per methanol molecule and the binding free energy per methanol molecule of the solvated ferrous ion in methanol are -142.1, -140.3 and -104.0 kJ mol(-1), respectively. For the clustering energies, we reported -6.9, -6.8 and -3.4 kJ mol(-1) corresponding respectively to the clustering electronic energy, the clustering enthalpy and the clustering free energy of the solvated ferrous ion in methanol. (C) 2022 Elsevier B.V. All rights reserved.