Effect of Hydrogen Bonding on Molecular Structure

Abstract

Hydrogen-bond formation modifies the electronic structure of the molecules involved. In very strong hydrogen bonds, the covalent X-H bond may be so much lengthened that it is barely distinguished from the H···A hydrogen bond, as shown in Part IB, Chap. 7, Table 7.2. This perturbation of the electronic structure of the donor bond and the acceptor atom will extend to the adjacent covalent bonds, depending upon the polarizability of the covalent bonding in the molecule. For this reason it is greatest in conjugated systems, where it is a structural manifestation of the π-bond cooperative effect, discussed in Chap. 1.