There is a joke among chemists that the ‘terminology’ of hydrogen bonding is created or used when they can not explain clearly for the unusual interaction of molecules, e.g. HF–HF.
This may be contrasted with covalent bonding (as in the H2 molecule), ionic bonding (as in KCl molecule in the gas phase), and London dispersion forces (as in Ar2). Hydrogen bonding is used by various scientists to describe interactions in extremes that can be summarized beautifully by an isoelectronic series, (FHF)-, HF•••HF, and Ne•••HF, suggested by Legon. In (FHF)-, we have a very strong hydrogen bond with a binding energy of 167 kJ mol-1, that borders a covalent bond. In HF•••HF, we have a typical hydrogen bond with a binding energy of 19 kJ mol-1, that is dominated by electrostatic forces. Finally in Ne•••HF, we have a weak interaction with a binding energy of 1 kJ mol-1, dominated by dispersive and inductive forces. Read the rest of this entry »
