A thermodynamic calculation of the electron work function and the composition of the charge component of a saturated vapor has been performed for congruently evaporated alkali metals and Na3AlF6. It has been shown that similar calculations are valid for alkaline-earth metal oxides.

New values for the standard enthalpies of formation of titanium fluorides at 0 K have been obtained by revisiting data on homogeneous and heterogeneous equilibria with their participation (kJ/mol): –1403.2 ± 2.7 for TiF 3 (c), –1144.2 ± 3.3 for TiF 3 , –2349.4 ± 6.3 for Ti 2 F 5 (c); –933.7 ± 6.8 for TiF 2 (c), and –650.4 ± 2.4 TiF 2 . The thermodynamic metastability of TiF 2 (c) has been shown.

A critical analysis of the literature data on equilibria of gas-phase reactions involving scandium fluorides and calcium and barium monofluorides has been carried out. The most reliable values of ∆fH°(0) for gaseous ScF3 (–1251 ± 15 kJ/mol), ScF2 (–683 ± 10 kJ/mol), and ScF (–141 ± 6 kJ/mol) are recommended. These values and sequential Sc–F bond dissociation energies are in good agreement with the data of quantum mechanical calculations.

Contradictory literature data on thermal stability, some methods of synthesis, and thermodynamic characteristics of nitryl fluoride have been considered and analyzed. Reliable estimates of reaction enthalpies have been obtained: 2FNO 2 = 2FNO + O 2 , Δ r H °(0) ≥ 173.5, NO 2 + 2CoF 3 (c) = FNO 2 + Co 2 F 5 (c), Δ r H °(0) = –7.4; 3/2N 2 O 4 + NaF(c) = FNO 2 + NO + NaNO 3 (c), Δ r H °(0) = 11.3 kJ/mol. A new value of the enthalpy of formation of nitryl fluoride Δ f H °(FNO 2 (g), 0) = –161 ± 15 kJ/mol has been recommended. For the interaction of FNO 2 with V 2 O 5 (c) as an example, the impossibility of formation of crystalline vanadium pentafluoride has been demonstrated.

Contradictory literature data on thermal stability, some methods of synthesis, and thermodynamic characteristics of nitryl fluoride have been considered and analyzed. Reliable estimates of reaction enthalpies have been obtained: 2FNO2 = 2FNO + O2, ΔrH°(0) ≥ 173.5, NO2 + 2CoF3(c) = FNO2 + Co2F5(c), ΔrH°(0) = –7.4; 3/2N2O4 + NaF(c) = FNO2 + NO + NaNO3(c), ΔrH°(0) = 11.3 kJ/mol. A new value of the enthalpy of formation of nitryl fluoride ΔfH°(FNO2(g), 0) = –161 ± 15 kJ/mol has been recommended. For the interaction of FNO2 with V2O5(c) as an example, the impossibility of formation of crystalline vanadium pentafluoride has been demonstrated.

На примере конгруэнтно испаряющихся галогенидов щелочных металлов и Na 3 AlF 6 проведен термодинамический расчет их работ выхода электрона и состава заряженной компоненты насыщенного пара. Показана применимость аналогичных расчетов для оксидов щелочноземельных металлов.

The experimental data on the joint fluorination of metallic iridium and platinum with molecular fluorine in the temperature range 654–880 K have been analyzed. The reasons for the decrease in the thermodynamic activity of metals and the possibility of the formation of new phases on their surfaces have been quantitatively considered. The Δ r H °(0) of reactions, kJ/mol, have been determined: Ir(c) + PtF 4 (g) = IrF 4 (g) + Pt(c), 23.0 ± 4.5; Ir(c) + 2IrF 6 (g) = 3IrF 4 (g), 217.7 ± 8.6; Ir 2 F 6 (c) + IrF 6 (g) = 3IrF 4 (g), 396.2 ± 21.3. The standard enthalpies of formation of the following iridium fluorides have been recommended: Δ f H °(Ir 2 F 6 , c, 0) = ‒1012.6 ± 15.5 kJ/mol, Δ f H °(IrF 4 , g, 0) = –482.3 ± 7.7 kJ/mol, and Δ f H °(IrF 6 , g, 0) = –832.3 ± 12.7 kJ/mol.

Detailed analysis is carried out for the set of experimental data, including those given in most recent publications, on the gas-phase and heterogeneous equilibria of reactions involving lower chromium fluorides. The causes for discrepancies between the same thermodynamic characteristics of compounds obtained in various studies are considered. The results of the analysis are presented as corrected enthalpies of formation of crystalline and gaseous compounds: ΔfH°(CrF, g, 0) = –42.5 ± 15.1 kJ/mol, ΔfH°(CrF2, cr, 298.15 K) = –780.7 ± 2.5 kJ/mol, ΔfH°(CrF2, g, 0) = –454.7 ± 4.6 kJ/mol, ΔfH°(CrF3, cr, 298.15 K) = –1146.7 ± 4.2 kJ/mol, and ΔfH°(CrF3, g, 0) = –799.9 ± 12.1 kJ/mol. The possibility of formation of crystalline Cr2F5 upon reduction of CrF3(cr) was confirmed.

The paper presents critical analysis of experimental data, including the most recent published data on the gas-phase and heterogeneous equilibria of reactions involving higher chromium fluorides. The results of the analysis are presented as the enthalpies of formation (kJ/mol) of chromium fluorides in the condensed and gas phases: ΔfH°(CrF4, cr, 298.15 K) = –1202.5 ± 12.8; ΔfH°(CrF4, a, 298.15 K) = –1193.5 ± 13.1; ΔfH°(CrF4, g, 0) = –1098.9 ± 12.1; ΔfH°(CrF5, cr, 298.15 K) = –1243.8 ± 12.4; ΔfH°(CrF5, g, 0) = –1150.5 ± 12.1. The standard enthalpy of formation of chromium hexafluoride in the gas phase was determined to be ΔfH°(CrF6, g, 0) = –1077 kJ/mol. The possibility of existence of the mixed crystalline fluoride CrIVCrVF9 was demonstrated and its enthalpy and entropy of formation from crystalline CrF4 and CrF5 were estimated to be ∆rH°(298.15 K) = –12.6 kJ/mol, ∆rS°(298.15 K) = –1.5 J/(mol K). The recommended values provide explanation for the thermal behavior of higher chromium fluorides and the possibility of conducting some procedures with them in the processes that are qualitatively described in available literature.

Literature data on the existence of mixed fluorides of 3 d elements M(II)M(III)F 5 (M = Mn, Fe, Co, Ni) were analyzed. Heterogeneous equilibria in MF 2 –MF 3 systems were considered, and equilibrium constants and enthalpies were calculated for the reactions with participation of M 2 F 5 (c). The FeF 2 sublimation enthalpy of 268.7 ± 1.9 kJ/mol was confirmed, and the FeF 3 (c) sublimation enthalpy was essentially refined, equal to 264.5 ± 2.2 kJ/mol. For crystalline fluorides Mn 2 F 5 , Fe 2 F 5 , Co 2 F 5 , and Ni 2 F 5 , the standard formation enthalpies were determined as equal to –1909.0 ± 7.8, –1716.3 ± 4.4, ≥–1554.2 ± 11, and –1370.5 ± 8.0 kJ/mol, respectively, at 0 K. The enthalpies and Gibbs energies of formation of these compounds from crystalline MF 2 and MF 3 were within a range of values typical for the solid solutions with weak interaction.

The fluorination of metallic platinum and of cobalt(II) and nickel(II) fluorides with nonequilibrium mixtures of F 2 containing high percentages of F is considered in terms of the acquisition of thermodynamic equilibrium. The enthalpy of the reaction Ni 2 F 5 (cr) = 2NiF 2 (cr) + 1/2F 2 (g) was determined by an independent method to be Δ r H °(0) = –59.9 ± 1.5 kJ/mol, and the enthalpy of formation was verified: Δ f H °(Ni 2 F 5 (cr), 0 K). A correlation was shown between the experimentally determined sequences of reactions that occur inside a nickel effusion cell and their enthalpies.

The literature data on thermal behavior of crystalline nickel fluorides NiF 3 and Ni 2 F 5 in the higher oxidation states are analyzed. Their enthalpies of formation are calculated: Δ f H o (Ni[NiF 6 ](cr), 0 K) = -1399.6 ± 6 and Δ f H o (Ni 2 F 5 (cr), 0 K) = −1370.5 ± 8 kJ/mol. The partial saturated vapor pressures in the NiF 3 –Ni 2 F 5 and Ni 2 F 5 –NiF 2 systems over a broad temperature range are determined. The technical impossibility to achieve a measurable pressure of NiF 3 is shown. The findings are compared to the data for similar derivatives of 3d-block elements and ruthenium and platinum trifluorides. Ni 2 F 5 (cr) is suggested to be used as a fluorine accumulator.

The literature data on equilibrium with the participation of cobalt fluorides and their negative ions are analyzed. Enthalpies of formation −∆fH°(0 K) are determined (kJ/mol): CoF3, 568.9 ± 8; $${\text{CoF}}_{3}^{ - }$$ , 972.4 ± 10; CoF4, 639.4 ± 12; $${\text{CoF}}_{4}^{ - }$$ , 1228.0 ± 17.