Mass-spectrometric determination of the enthalpies of dissociation of gaseous complex fluorides into neutral and charged particles. VIII. MF-GaF 3 systems (M = Li, Na, K, Rb, Cs)

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Knudsen cell mass spectrometry has been applied to the study of ion/molecule equilibria between the negative ions AlF 4 −, GaF 4 −, Ga 2F 7 −, GaAlF 7 − and molecules of gallium and aluminium trifluorides. The thermodynamic quantities Δ H f,298 0 (GaF 4 −) = −1638.0±32.2 kJ mol − Δ H f,298 (Ga 2F 7 −) = −2776.5±47.5 kJ mol −1 Δ H f,298 0 (GaALF 7 −) = −3092.0±37.0 kJ mol −1 were calculated from the experimental data. For the system GaF 3+F − = GaF 4 −, Δ H 298 0 = −461.5±17.2 kJ mol −1. The enthalpies of dissociation of complex molecules MGaF 4, where M is an alkali metal, into neutral and charged particles have been estimated.