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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. May 2004, Volume 3, Number 5, 222-232 |
η5- and η6-Coordinations Revisited:
An ELF Study of Ferrocene and Dibenzenechromium
Gilles Frison and Alain Sevin
Internet Electron. J. Mol. Des. 2004, 3, 222-232
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Abstract:
The chemistry of five-membered and six-membered conjugated
cyclic ligands complexes belongs to the most important classes
of organometallic compounds. The determination of the precise
nature of the metal-ligand bond is of great importance for the
synthesis of new compounds and understanding of their
reactivity. We propose here a topological ELF analysis of the
metal-ligand interaction with a comparative model study of η5-
and η6-coordination respectively in ferrocene and
dibenzenechromium. Electron Localization Function (ELF)
offers a reliable measure of electron pairing and localization. An
ELF calculation partitions molecular space in terms of attractors
and basins. Each basin, located around an attractor, could be
clearly identify into series, each of then having a precise
significance (core, lone pair, two-center bond, three-center bond,
…). This work shows that both η5- and η6-coordinations could
be decomposed in a sum of η1- and η2-interactions, the latter
being predominant. The bonding description is in agreement with
the classical resonance scheme. The topological analysis of the
ELF function provides a basis for interpreting and visualization
of the bonding scheme in model sandwich molecules. TopMoD
package is available free of charge at
http://www.lct.jussieu.fr/silvi/topmod_english.html.
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