Fundamental Features of Hydrogen Bonds

Department of Chemistry, Mailcode 4409, Southern Illinois University, Carbondale, IL 62901, U.S.A. 

More than half a century has elapsed since Linus Pauling discussed his ideas about the fundamental nature and properties of the hydrogen bond in his landmark book [1]. Pauling had based these ideas on the information that was available at the time. He made reference to papers going back as far as 1912 [2] in which the presence of such an interaction was inferred from the weakness of a particular base. In 1920, mention was made of the widespread occurrence of H-bonds [3], in connection with anomalous properties of certain liquids. Most of the information that had accumulated up to 1940 was based on the structures found in crystals, infrared spectroscopic data in solution, and various other physical-chemical data. 

A more subtle feature described by Pauling later became known as the cooperativity effect a chain of n consecutive H-bonds is generally stronger than n individual H-bonds in isolation from one another. He delved into the unusual characteristics of very short, ionic H-bonds such as (FHF) , questioning whether the equilibrium position of the proton is precisely midway between the two F nuclei. Pauling also indicated that H-bonds did not have to involve two different molecules it was deemed possible for two groups within the same molecule to form a H-bond with one another. 

This chapter celebrates the wisdom and chemical intuition of Linus Pauling. We will reexamine several of his notions about the hydrogen bond to see how well they have withstood the test of time, and the enormous amount of data accumulated from new experimental and theoretical methods that were not available to him in 1940. 

---