Thermodynamics of dihydrogen bonds (A-H•••H-B)

Ab initio molecular orbital calculations at the G1 and G2 levels of theory have been performed for dihydrogen bonded complexes AH ... HB pairing molecules with electron-rich hydrogen atoms (LiH, BeH2) and compounds containing electron positive H atoms (HF, HCN, HCCH). Of the two, the LiH forms the stronger dihydrogen bond with electron donors HF, HCN and HCCH. Absolute values of gas-phase interaction enthalpies and free energies computed by the G1 and G2 methods were comparable in accuracy.