Insight into the Bonding and Aggregation of Alkyllithiums by Experimental Charge Density Studies and Energy
Annika Münch1, Lena Knauer2, Holger Ott3
1Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstraβe 4, Göttingen 37077, Germany.
Abstract:
In this Article, the organolithiums [((-)-sparteine)LiBu] (1), [(ABCO)LiBu]2 (2), and [(ABCO)2(LiPr)4] (3) are investigated by means of experimental and theoretical charge density determination to elucidate the nature of the Li-C and Li-N bonds. Furthermore, the valence shell charge concentrations (VSCCs) in the nonbonding region of the deprotonated Cα-atom will provide some insight on the localization of the carbanionic lone pair. Analysis of the electron density (ρ(rBCP)), Laplacian (∇2ρ(rBCP)), and the energy decomposition (EDA) confirmed that the Li-C/N bond exhibits astonishingly similar characteristics, to reveal an increasingly polar contact with decreasing aggregate size. This explains former observations on the incorporation of halide salts in organolithium reagents. Furthermore, it could be shown that the bonding properties of the Pr group are similar to those of the Bu substituent. The accuracy of fit to all previously determined properties in organolithiums is remarkable.
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