Principles of Structural Bonding

Principles of structure, bonding and reactivity for metal nitrosyl complexes. J. H. Enemark and R. D. Feltham, Coord. Chem. Rev., 1974,13, 339-406 (126). 

In 1923. Lewis published a classic book (later reprinted by Dover Publications) titled Valence and the Structure of Atoms and Molecules. Here, in Lewis s characteristically lucid style, we find many of the basic principles of covalent bonding discussed in this chapter. Included are electron-dot structures, the octet rule, and the concept of electronegativity. Here too is the Lewis definition of acids and bases (Chapter 15). That same year, Lewis published with Merle Randall a text called Thermodynamics and the Free Energy of Chemical Substances. Today, a revised edition of that text is still used in graduate courses in chemistry. 

The principal interest of the rubber hydrochloride structure (apart from its bearing on the theory of the relation between the physical properties and the molecular structure of polymers) is that it formed the first test of validity and usefulness of the principle of staggered bonds. Abnormal structures f In all the structures considered so far two... 

Most of the general principles of molecular structure and the nature of the chemical bond were formulated long ago by chemists by indue-tion from the great body of chemical facts. During recent decades these principles have been made more precise and more useful through the application of the powerful experimental methods and theories of modem physics, and some new principles of structural chemistry have also been discovered. As a result structural chemistry has now become significant not only to the various branches of chemistry but also to biology and medicine. 

Although molecules are held together by bonds that are predominantly covalent, many substances are made up of ions that are arranged in a crystal lattice. These materials are held together in the solid state by forces that are essentially electrostatic in character. In some cases, the forces arise from the transfer of electrons between atoms to produce ionic materials. However, in most cases the ions are somewhat polarizable (especially anions), so the ions have distorted structures that represent some degree of electron sharing. As a result, many of the forces in crystals that are normally considered to be ionic may be appreciably less than completely ionic. This fact should be kept in mind as the principles of ionic bonding are discussed. 

Pauling, L. The Nature of the Chemical Bond, 3rd ed., Ithaca, NY Cornell University Press, 1960. A comparison of the valence bond approach with other theories as applied to transition metal complexes can be found in Huheey, J.E. Inorganic Chemistry Principles of Structure and Reactivity. New York Harper and Row, 1972. 

One currently held view about organic chemistry that seems to be receiving broad acceptance is that for organizational purposes, it can best be divided into three main areas. These areas are structure, dynamics, and synthesis, and they are interdependent. In order to appreciate fully the latter two areas, both of which will be developed at length in subsequent chapters, a firm grounding in the principles of structure and chemical bonding is essential. 

In the case of functional groups we need to have a toolbox of reactions from which to choose those we know can convert one given functional group into another. You will develop such a toolbox of reactions as you proceed through your study of organic chemistry. Similarly, with regard to making carbon-carbon bonds in synthesis, you will develop a repertoire of reactions for that purpose. In order to choose the appropriate reaction for either purpose, you will inevitably consider basic principles of structure and reactivity. 

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