The three-electron theory of bond accepted for granted the existence of three-electron bonds (one axiom), everything else is derived logically.
And if think… reflect the existence of three-electron bond directly from the theory of resonance (resonance structures do not exist, in reality there is something average between them — and now think that should really be the basis of this, some real structure?.. of course the three-electron bond!!!).
Hückel rule (4n +2) for aromatic systems can be written in a different form, in the form of 2n where n — unpaired number. So, we have: 2, 6, 10, 14, 18, etc. This is also true for the electron shells in the atom and aromatic systems. The principle of the interaction of fermions always one, everywhere.
I note that the three-electron bond to describe the benzene molecule used even W.O. Kermak, R. Robinson and J. J. Thomson at the beginning of the 20th century. Here are links to their works:
1. Thomson, J. J. Philosophical Magazine, 1921, 41, 510—538.
2. W.O. Kermak and R. Robinson, J. Chem. Soc. 427 (1922).
But since it is not taken into account the spin of electrons, we have already started cyclooctatetraene problems and therefore the description of the benzene molecule by a three-electron proved unsuccessful.
Using the three-electron bond with multiplicity of 1.5 and take account of the spin of each electron leads to very good results in the description of the benzene molecule and explain the aromaticity in general. With the help of three-electron bond with multiplicity of 1.5 can be represented by a real formula of many organic and inorganic molecules without the aid of virtual structures.
Theory of three-electron bond is constantly evolving and is used in organic and inorganic chemistry. Below I give links to some work of scientists who have made an invaluable contribution to the development of application and understanding of the three-electron bond:
1. J.W. Linnett (a) J. Amer. Chem. Soc. 83, 2643 (1961). (B) The Electronic Structures of-Molecules, (Methuen, London, 1964). (C) Science Progress (Oxford) 60, 1 (1972).
2. Linus Pauling. The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry 3rd Edition. Copyright 1939 and 1940, third edition. 1960 by Cornell University.
3. R. D. Harcourt. Qualitative Valence-Bond Descriptions of Electron-Rich Molecules: Pauling «3-Electron Bonds» and «Increased-Valence» Theory. Springer-Verlag Berlin Heidelberg New York 1982.
4. Pauling’s Legacy. Modern Modelling of the Chemical Bond. Edited by Z. B. Maksic. ELSEVIER 1999.
3 сентября 2016 г., в 10:24
Volodymyr Dmytrovich Bezverkhniy
Synthetic Chemist (Organic Chemistry). Lecturer (Organic Chemistry). Chemical Engineer.
Education: Yuriy Fedkovych Chernivtsi National University, Department of chemistry. Chemistry/Organic Chemistry, 1989 — 1994. Master’s Degree, with honors. Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine. Graduate School. Organic Chemistry, 1997 — 2001.