Thermodynamic properties of lanthanum and lanthanide halides:: IV.: enthalpies of atomization of LnCl, LnCl+, LnF, LnF+, and LnF2

The results of measurement of equilibrium constants of 30 reactions involving lanthanum and lanthanide fluorides (LnF, LnF(2), and LnF(3)) and 14 reactions involving lanthanum and lanthanide monochlorides (Ln = La-Lu) have been summarized. These constants have been used for calculating the enthalpies of reactions by the second and third laws, from which the enthalpies of atomization Delta H-at(0)0 of LnCl, LnF, and LnF(2) have been determined. Comparison of the calculation results shows that the thermodynamic functions of LnCl and LnF (Ln = Ce-Yb) in which the electronic excitation contribution has been calculated from the excitation energies of Ln(+) ions allow one to adequately determined the Delta H-at(0)0 values from experimental data. Using the trends in the change in Delta H-at(0)0 as a function of the atomic number of a lanthanide, the enthalpies of atomization of compounds for which experimental data are lacking have been estimated. The Delta H-at(0)0 values for LnCl(+) ions have been calculated. The reliability of the Delta H-at(0)0 values for LnF(+) ions have been assessed.