Thermodynamic properties of hydrogen-bonded dimers B⋯HF from spectroscopy: B = HCN, CH3CN, HC2CN, (CH3)3CCN and H2O

Abstract

The rotational and vibrational spectra of several hydrogen-bonded dimers BHF have now been investigated in sufficient detail to allow the thermodynamic properties of BHF to be evaluated with useful accuracy. Dissociation energies D₀ for dimers BHF are known from the measurement of absolute intensities of rotational transitions in equilibrium gas mixtures of B, H and BHF. Together with vibrational separations and rotational constants, the D₀ have been used to estimate ΔH _m(T) for the reaction B + HF = BHF where B = HCN, CH₃CN, HC₂CN, (CH₃)₃CCN and H₂O. The standard spectroscopic entropies S(T, M) have been evaluated for each participant M in the reaction and thence ΔS _m(T), ΔG _m(T) and K _m(T). Finally, standard functions for each BHF at 298.15 K are tabulated.