Enthalpies of Formation of Chromium Fluorides I. Lower Fluorides CrF, CrF 2 , and CrF 3

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: Δ f H °(CrF, g, 0) = –42.5 ± 15.1 kJ/mol, Δ f H °(CrF 2 , cr, 298.15 K) = –780.7 ± 2.5 kJ/mol, Δ f H °(CrF 2 , g, 0) = –454.7 ± 4.6 kJ/mol, Δ f H °(CrF 3 , cr, 298.15 K) = –1146.7 ± 4.2 kJ/mol, and Δ f H °(CrF 3 , g, 0) = –799.9 ± 12.1 kJ/mol. The possibility of formation of crystalline Cr 2 F 5 upon reduction of CrF 3 (cr) was confirmed.