Communication theory of the chemical bond

R.F. Nalewajski, Comparison between valence-bond and communication theories of the chemical bond in H2, Mol. Phys. 104 (2006) 365. 

R.F. Nalewajski, On molecular similarity in communication theory of the chemical bond, J. Math. Chem. 45 (2009) 607. 

The first chapter reviews information theoretic methods applied to determination of molecular electronic structure in the context of the Orbital Communication Theory of the chemical bond. The molecule is treated as an information network from which structural information can be obtained. The results of probing molecular charges and bond orders using this method are compared with results obtained by more commonly used means. 

The Communication Theory of the Chemical Bond (CTCB) has been developed using the basic entropy/information descriptors of molecular information (communication) charmels in the AIM, orbital and local resolutions of the electron probability distributirms [9-11, 33-48]. The same bond descriptors have been used to provide the information-scattering perspective on the intermediate stages in the electron redistribution processes [49], including the atom promotion via the orbital hybridization [50], and the communication theory for the excited electron configurations has been developed [51]. Moreover, a phenomenological treatment of equilibria in molecular subsystems has been proposed [9,52-54], which formally resembles the ordinary thermodynamic description. 

The problem discussed by Weiss, the nature of the iron-oxygen bond in oxyheemoglobin, was given a thorough discussion by me in two communications published about 15 years ago . It is now possible to amplify the discussion somewhat, in part because of further development of the theory of the chemical bond and in part because of the increased knowledge about the structure of oxy-hsemoglobin and related molecules that has been obtained by the X-ray diffraction investigations of Kendrew and Perutz . 

The argument of this and the following chapter is taken for the most part from my paper The Nature of the Chemical Bond Application of Results Obtained from the Quantum Mechanics and from a Theory of Paramagnetic Susceptibility to the Structure of Molecules/1 J.A.C.S. 53, 1367 (1931), and the preliminary communication, Proc. Nat. Acad. Sci. U. 14, 359 (1928). 

Entropic probes of the molecular electronic structure have provided attractive tools for describing the chemical bond phenomenon in information terms. It is the main purpose of this survey to summarize alternative local entropy/information probes of the molecular electronic structure [9-14, 21, 22] and to explore the information origins of the chemical bonds. It is also our goal to present recent developments in the AO formulation of CTCB, called the Orbital Communication Theory (OCT) [10,11, 39,48,55-58]. The importance of the nonadditive effects in the chemical-bond phenomena will be emphasized and the information-cascade (bridge) propagation of electronic probabilities in molecular information systems. 

Several works give an overview the development of the concept of affinity.155-158 There is an autobiographical narrative by Robert Mulliken (1896-1986), who contributed so decisively to the development of molecular orbital theory.159 There are also studies on a number of more specific bonding-mechanisms160-162 and on the reaction of the chemical community to hydrogen bonding.163... 

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