Dissociation energies of the hydrogen-bonded dimers RCN⋅⋅⋅HF (R=CH3, HCC) determined by rotational spectroscopy

Measurements of absolute intensities of rotational transitions have been used to determine the zero-point and equilibrium dissociation energies D0 and De of the hydrogen-bonded dimers CH3CN⋅⋅⋅HF and HCCCN⋅⋅⋅HF. For CH3CN⋅⋅⋅HF reported values are D0=26.1(0.6) kJ mol−1 and De=29.0(0.9) kJ mol−1 while for HCCCN⋅⋅⋅HF the corresponding values are 20.4(0.7) and 23.4(0.9) kJ mol−1, respectively. The De values are used in conjunction with De=26.1(1.6) kJ mol−1 previously obtained for HCN⋅⋅⋅HF to investigate the suitability of the Morse and Lennard-Jones functions for describing the hydrogen-bond radial potential energy.