An ab initio investigation of the properties of H2:HX hydrogen-bonded complexes
Eight complexes H2:HX formed with the σ-bond of the H2 molecule as the proton acceptor and proton donors HCCH, HCCLi, HCCF, HCN, HNC, H2O, HF, and HCl have been optimized at MP2/aug-cc-pVTZ. Analyses of the electron densities indicate that these are weakly-bound hydrogen-bonded complexes, in contrast to H2:HH which is a van der Waals complex. H–H bond stretching frequencies of the H2 molecule, 1H chemical shieldings, and indirect spin–spin coupling constants have been computed in order to identify the most promising spectroscopic tool for characterizing these complexes. The H2 stretching vibration is the property which is most sensitive to complex formation.