Thermochemistry of Cobalt Trifluoride

Abstract

The value Δ_fH₀° (CoF₃(cr)) = –861 ± 10 kJ/mol is determined using the data on equilibria of the reactions involving crystalline cobalt(III) fluoride. The features of chemical and thermal behavior of this compound (in particular, its easy hydrolyzability due to hygroscopic properties and vaporization without decomposition to fluorine and difluoride) are explained. The enthalpies of formation of crystalline and gaseous cobalt fluorides CoF_n (n = 2–4), as well as some of their negatively charged ions, and electron affinity energies of CoF₃ and CoF₄ (3.42 and 6.10 eV, respectively) are reported. Quantitative comparison of the efficiencies of iron, manganese, and cobalt trifluorides used as fluorinating agents to synthesize organic and inorganic compounds is performed.