The Nature of the Hydrogen Bond

Abstract Hydrogen bond (H-bond) effects are well known: it makes sea water liquid, joins cellulose microfibrils in sequoia trees, shapes DNA into chromosomes, and polypeptide chains into wool, hair, muscles, or enzymes. However, its very nature is much less known and we may still wonder why O-H···O energies range from less than 1 to more than 30 kcal/mol without evident reason. This H-bond puzzle is tackled here by a new approach aimed to obtain full rationalization and comprehensive interpretation of the H-bond in terms of classical chemical-bond theories starting from the very root of the problem, an extended compilation of H-bond energies and geometries derived from modern thermodynamic and structural…