Theory of the Hydrogen Bond

For the best and safest method of philosophizing seems to be first diligently to investigate the properties of things and establish them by experiment and then to seek hypotheses to explain them. For hypotheses ought to be fitted merely to explain the properties of things and not attempt to predetermine them except in so far as they can be an aid to experiments.  

The development of the theory of the H bond chemical interaction entered this last phase about two decades ago. Yet, in 1957 Coulson said, the most that can be expected is that calculations will give us indications as to those explanations which are most likely to be correct, 

1 Reviews of the Theory of Hydrogen Bonding. Reviews of the theory of the H bond are numerous. Inasmuch as the Russian literature is not always readily accessible, it is of special note that two such reviews concern Russian contributions that of Sokolov (1913, in German) and that of Magat (1317, in French). 

Discussion of the H bond theory is divided into two portions in this chapter. First, the nature of the bond itself is considered, together with the relevant and informative data. Second, theoretical treatments of individual properties of H bonded systems (such as heat of formation, vibrational perturbations, NMR shifts, dielectric effects) are considered in the light of the first part. Before proceeding with the discussion, however, it will be helpful to review certain aspects of modern theory of the chemical bond. 

2 Ionic and Covalent Bonds. In this chapter much is said on the question of whether the H bond is electrostatic in character. In this use, the term electrostatic denotes that the bond forms as a result of attractive coulombic interactions of charge separations existing prior to bond formation. It is important to note that the valence rules play no role in the explanation of the bonding. 

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Once again this is a very useful description for understanding molecular interaction. The normal form of the ice crystal, for example, is held together by hydrogen bonds in such a way that each molecule is surrounded tetrahedrally by four others.1 [ his is completely consistent with the electrostatic theory of the hydrogen bond according to which a proton is... 

Kollman PA, Allen LC (1969) Theory of the hydrogen bond electronic structures of properties of the water dimer. J Chem Phys 51 3286- 3293... 

Del Bene JE, Cohen I (1978) Molecular orbital theory of the hydrogen bond. 20. Pyrrole and imidazole as proton donors and proton acceptors. J Am Chem Soc 100 5285 - 5290... 

The explanation was provided by the theory of the hydrogen bond. According to this theory, two acetic acid molecules with the generally accepted structural formula could combine by forming two hydrogen bonds with one another, to produce a double molecule (called acetic acid dimer), as shown in the adjacent drawing. 

P. A. Kollman and L. C. Allen, Chem. Rev., 72, 283 (1972). The Theory of the Hydrogen Bond. See also, S. Scheiner, this volume. Calculating the Properties of Hydrogen Bonds by ab Initio Methods. 

The fifth part discusses the theory of intermolecular interactions. Again, London is an influential figure here. In fact, his first paper with Heitler on the theory of the hydrogen bond was a spinoff of an earlier attempt to solve the problem of van der Waals interactions. 

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