Département de Chimie Physique, Sciences II, 30 quai E.-Ansermet 30 – 1211 Genève 4 / Tél 022 379 68 04

Genève, le 3 janvier 2007/sj

LE DEPARTEMENT DE CHIMIE PHYSIQUE

a le plaisir de vous inviter à la

CONFERENCE

intitulée

THE NATURE OF THE CHEMICAL BOND –OLD QUESTIONS, NEW ANSWERS

donnée par

Prof. Gernot FRENKINGFachbereich Chemie der Philipps-Universität Marburg

le MARDI 8 MAI 2007 à 16h30

SALLE A100Sciences II

30 quai E.-Ansermet

Responsable : Prof. Laura Gagliardi

Département de Chimie Physique, Sciences II, 30 quai E.-Ansermet 30 – 1211 Genève 4 / Tél 022 379 68 04

Abstract. The nature of the chemical bond is presented in most chemistry textbooks with a

mixture of heuristic bonding models which have been proven helpful for the interpretation and

classification of molecular structures and reactivities. However, the MO and VB models often

neglect important knowledge about the physical origin of the chemical bond which has been

gained in theoretical studies by Hellmann, Hirshfeld, Ruedenberg, Kutzelnigg, Schwarz and

other scientists. There is a gap between the heuristic bonding models which are used by

chemists and the physical mechanism which yields a chemical bond. In my lecture I will

present the results of an energy decomposition analysis (EDA) of chemical bonds in

transition metal complexes and molecules of main group elements. The EDA data make it

possible to characterize chemical bonds quantitatively in terms of electrostatic and covalent

bonding. It is also possible to address the question whether a bond is a single or multiple bond.

The EDA results can be used by chemists as model for the chemical bond which is in

agreement with the physics that is behind the bonding interactions.1 Very recently, the EDA

was found to be particularly helpful for estimating the strength of conjugation,

hyperconjugation and aromaticity.2

1. (a) A. Krapp, F. M. Bickelhaupt, G. Frenking, Chem. Eur. J., ASAP. (b) M. Lein and G.

Frenking, Theory and Applications of Computational Chemistry: The First 40 Years, p. 291,

C.E. Dykstra, G. Frenking, K.S. Kim, G.E. Scuseria (Eds), Elsevier, Amsterdam, 2005. (b) A.

Kovács, C. Esterhuysen, G. Frenking, Chem. Eur. J. 2005, 11 , 1813. (c) Frenking, G.;

Wichmann, K.; Fröhlich, N.; Loschen, C.; Lein, M.; Frunzke, J.; Rayón, V.M. Coord.

Chem. Rev. 2003, 238-239, 55.

2. (a) D. Cappel, S. Tüllmann, A. Krapp, G. Frenking, Angew. Chem. 2005,117, 3683; Angew.

Chem. Int. Ed. Engl. 2005, 44, 3617. (b) . I. Fernández and G. Frenking, J. Org. Chem., 2006,

71, 2251. (c) I. Fernández and G. Frenking, Chem. Eur. J. 2006, 12, 3617. (d) I. Fernández

and G. Frenking, Faraday Disc. 2007, 135, 403.