Is There Anything New
in Chemical Bonding? New Bonding Concepts from Valence Bond Theory
Sason Shaik, Department of
Organic Chemistry and the Minerva Center for Computational Quantum Chemistry,
The Hebrew University, 91904 Jerusalem, Israel
e-mail:
Lundi 21 mai 2001, 11h00
The concept of the electron-pair bond was formulated in a
stroke of genius by G.N. Lewis in his famous 1916 JACS paper.1 In 1927
W. Heitler and F. London published their seminal paper on the origin of
the homopolar electron-pair bond in H2.2
This work has eventually led
to the colossal intellectual construct of Pauling on the nature of the
chemical bond,3 in which the bond is regarded in terms of valence bond
(VB) theory as a superposition of covalent and ionic bonding. In
essence, this was a quantum chemical version of Lewis's electron-pair
theory. Molecular orbital theory has retrieved the same picture in
terms of the static charge polarization of the bond orbital. Now that
our bonding paradigms are 85 years old, one may wonder if this is the
entire story. New bonding features derived in our group from VB
theory,4,5 such as charge-shift bonding and ferromagnetic
bonding5 and their chemical manifestation will be described and discussed.
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[1] Lewis, G. N. J. Am. Chem. Soc.
1916, 38, 762.
[2] Heitler, W.;
London, H.F. Physik 1927,
44, 455.
[3] Pauling, L. The Nature of the
Chemical Bond; 2nd ed.; Cornell University Press: Ithaca,
N.Y., 1940.
[4] Shaik, S.; Maitre, P.; Sini, G.; Hiberty,
P. C. J. Am. Chem. Soc. 1992,
114, 7861.
[5] Danovich, D.; Wu, W.; Shaik, S.
J. Am. Chem. Soc. 1999,
121, 3165.