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A Pair of Lonely Electrons in a Crowded Room: Revisiting the Concept of an Electron Lone-Pair

06-10 February 2023

University of Pretoria
South Africa
13:00 CET 08-Feb-23

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Dr. Jurgens de Lange

University of Pretoria, South Africa

Electron pairs are a ubiquitous concept in chemical bond theory: from covalent and non-covalent interactions to resonance and the Pauli Exclusion Principle, electron pairs from the cornerstone of electronic structure. In particular, electron lone-pairs play determining roles in describing geometric structure, reactivity and dative-covalent bonds. The concept of an atom-localized lone-pair, however, conflicts with the molecular-wide wave-nature of electrons, leading to the hypothesis that all lone-pairs are at least somewhat delocalized over multiple atoms. Unfortunately, exact quantification of the degree of lone-pair (de)localization is quite difficult.
Here, we apply the Fragment, Atomic, Localized, Delocalized and Interatomic (FALDI)1 density decomposition scheme to the quantification and visualization of lone-pairs. We show, in a series of model compounds (including primary amines, donor-acceptor compounds and organometallic bonds) that lone-pairs can be considerably more delocalized than what previous models might suggest. We discuss the nature of lone-pair delocalization and show that an intact lone-pair localized to an atom can couple to a lone-pair split amongst two atoms to increase its delocalization in a polarized fashion.

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Keywords: Electron delocalization, chemical bond theory, FALDI, theoretical chemistry

 


References

[1] - de Lange, J. H.; Cukrowski, I. J. Comp. Chem. 2018, 39, 1517–1530

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Financial Support

The 2025 edition of the Virtual Winter School on Computational Chemistry is proudly sponsored by the School of Chemistry at the University of Edinburgh.


The Cooper Union for the Advancement of Science and Art is pleased to provide support for the 2024 VWSCC through a generous donation from Alan Fortier.

We thank Leibniz Institute for Catalysis (LIKAT) and CECAM for their support.