The theory of resonance

Page J B 1991 Many-body problem to the theory of resonance Raman scattering by vibronic systems Top. Appi. Phys. 116 17-72... 

The strength of the bonding found in the actual structure III is greater than that calculated for either of the imaginary structures I and II. This has been explained on the theory of resonance based... 

The convenience and usefulness of the concept of resonance in the discussion of chemical problems are so great as to make the disadvantage of the element of arbitrariness of little significance. Also, it must not be forgotten that the element of arbitrariness occurs in essentially the same way in the simple structure theory of organic chemistry as in the theory of resonance — there is the same use of idealized, hypothetical structural elements. In the resonance discussion of the benzene molecule the two Kekule structures have to be described as hypothetical it is not possible to synthesize molecules with one or the other of the two Kekule structures. In the same way, however, the concept of the carbon-carbon single bond is an idealization. The benzene molecule has its own structure, which cannot be exactly composed of structural elements from other molecules. The propane molecule also has its own structure, which cannot be composed of structural elements from other molecules — it is not possible to isolate a portion of the propane molecule, involving parts of two carbon atoms... 

The polar character of the group R will also have a bearing on the formation and stabilization of the furan ring. In accordance with the theory of resonance, the classic structure... 

The classic HLSP-PP-VB (Heitler-London-Slater-Pauling perfect-pairing valence-bond) formalism and its chemical applications are described by L. Pauling, The Nature of the Chemical Bond. 3rd edn. (Ithaca, NY, Cornell University Press, 1960 G. W. Wheland, The Theory of Resonance (New York, John Wiley, 1944) and H. Eyring, J. Walter, and G. E. Kimball, Quantum Chemistry (New York, John Wiley, 1944). 

The theory of resonance-assisted coupling of H-bonding and torsions... 

An MNF/microcylinder sensor exploits WGMs resonances in a cylinder (optical fiber), which are excited by an MNF. The arrangement of an MNF and a cylinder is shown in Fig. 13.li. As opposed to the WGM in a microsphere and microdisk considered in Sect. 13.3.1, the beam launched from the MNF into the cylinder spreads along the cylinder surface and eventually vanishes, even if there is no loss. The theory of resonant transmission of the MNF/microcylinder sensor was developed in Ref. 18. The resonant transmission power of this device can be modeled by a self-interference of a Gaussian beam that made n turns along the cylinder circumference ... 

Linus Pauling, "The Nature of the Theory of Resonance," 18, in [Sir] Alexander Todd, ed., Perspectives in Organic Chemistry (New York Interscience Publishers, 1956) 67, regarding Ingold and Ingold (1926), 1312. Todd s volume is dedicated to Robert Robinson on the occasion of his seventieth birthday, September 13, 1956. 

Classical structure theory was developed purely from chemical facts, without any help from physics. The theory of resonance was well on its way toward formulation before quantum mechanics was discovered.. . . ... 

It is true that the idea of resonance energy was then provided by quantum mechanics. . . but the theory of resonance in chemistry has gone far beyond the region of application in which any precise quantum mechanical calculations have been made, and its great extension has been almost entirely empirical.. . . The theory of resonance in chemistry is an essentially qualitative theory, which, like the classical structure theory, depends for its successful application largely upon a chemical feeling that is developed through practice. 46... 

Wheland, G. W. A Quantum Mechanical Investigation of the Orientation of Substituents in Aromatic Molecules. J. Amer. chem. Soc. 64, 900 (1942). 139- — The Theory of Resonance. New York Wiley 1944. 

The theory of resonance transfer of electronic excitation energy between donor and acceptor molecules of suitable spectroscopic properties was first presented by Forster.(7) According to this theory, the rate constant for singlet energy transfer from an excited donor to a chromophore acceptor which may or may not be fluorescent is proportional to r 6, where r is the distance... 

L. Pauung (Pasadena) I should like to object to the use by Dr. Pople of the expression the presence of the structures in the hydrogen bond . I think that one must be careful to use expressions such as 4 the contribution of the structures. . in order that listeners should not be misled as to the nature of the theory of resonance. 

A thorough and penetrating discussion of the theory of resonance is given in the book by George Willard Wheland, Resonance in Organic Chemistry, John Wiley and Sons, New York, 1955. Other valuable reference books are Y. K. Syrkin and AT. E. Pvatkina, Structure of Molecules and the Chemical Bond, Interscience Publishers, New York, 1950, and C. A. Coulson, Valence, Clarendon Press, Oxford, 1952. 

Moreover, it must not be forgotten that the element of arbitrariness occurs in essentially the same way in the simple structure theory of organic chemistry as in the theory of resonance there is the same use... 

Une of the most interesting and useful applications of the theory of resonance is in the discussion of the structure of molecules for which no one valence-bond structure is satisfactory. An introduction to this discussion is presented in the following sections. The chapter ends with a reply to some critical comments that have been made about the theory. 

The essential identity in character of the theory of resonance and the classical structure theory of organic chemistry, which has before been referred to only briefly,42 will be discussed in detail in the following paragraphs. 

The theory of resonance has been applied to many problems in chemistry. In addition to its use in the discussion of the normal covalent bond (involving the interchange of two electrons, with opposed spins, between two atoms) and to the structure of molecules for which a single valence-bond structure does not provide a satisfactory description, it has rendered service to chemistry by leading to the discovery of several... 

The Russian criticism of the theory of resonance seems to be based largely upon the fact that the contributing resonance structures do not have real existence.44 Essentially the same point is made in HiickeFs book Structural Chemistry of Inorganic Compounds Kh in the last paragraph of V.olume I, in a note of criticism of the theory of resonance supplied by the translator of the English edition, L. H. Long, the complaint is expressed in the following words ... 

Now let us consider benzene. There is no single valence-bond structure that accounts satisfactorily for the properties of benzene. The simple description of benzene that is given by the theory of resonance involves two valence-bond structures, the two Kekul6 structures... 

The several structures that are used in the description of a molecule such as be ci. by application of the theory of. resonance are idealizations, ivud aw/e existence in reality. This fact has been ad-... 

I feel that the greatest advantage of the theory of resonance, as compared with other ways (such as the molecular-orbital method) of discussing the structure of molecules for which a single valence-bond structure is not enough, is that it makes use of structural elements with which the chemist is familiar. The theory should not be assessed as inadequate because of its occasional unskillful application. 11 becomes more and more powerful, just as does classical structure theory, as the chemist develops a better and better chemical intuition about it. 

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