A COMPARATIVE THEORETICAL-STUDY OF THE ALLYL ALKALI-METALS
van Eikema Hommes N, Bühl M, Schleyer P, Wu YD (1991)
Publication Status: Published
Publication Type: Journal article
Publication year: 1991
Journal
Publisher: Elsevier
Book Volume: 409
Pages Range: 307-320
Journal Issue: 3
Abstract
The ab initio structures calculated for the Li-Cs series of allyl alkali metal compounds prefer symmetrically bridged geometries. Bonding is mainly electrostatic; the natural charges on the metals range from 0.910 (Li) to 0.999 (Cs). Dimerization and solvation, which were studied for allyllithium, result in longer bonds to the metal. Rotational barriers, calculated for the monomers, show the uniform trends to larger values along the series, Cs > Rb > K > Na, as is found by experiment. The calculated barrier for monomeric allyllithium, out of line and also too high with regard to experiment, is lowered by dimerization and solvation. The reasons for the abnormally low 1J(C-H) coupling constants (e.g. 131-133 Hz for the central carbon for all alkali metals) have been disputed. Hybridizations given by the Natural Bond Orbital method are in reasonable agreement with those deduced from the usual empirical relationship 0.2 J(C-13-H) = %s. Model calculations on allyllithium and the allyl anion with imposed structural constraints show that CCC-angle widening is the main cause of the small coupling constants; hydrogen out-of-plane bending and sigma-polarization due to the pi-charge have smaller influences.
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APA:
van Eikema Hommes, N., Bühl, M., Schleyer, P., & Wu, Y.-D. (1991). A COMPARATIVE THEORETICAL-STUDY OF THE ALLYL ALKALI-METALS. Journal of Organometallic Chemistry, 409(3), 307-320.
MLA:
van Eikema Hommes, Nico, et al. "A COMPARATIVE THEORETICAL-STUDY OF THE ALLYL ALKALI-METALS." Journal of Organometallic Chemistry 409.3 (1991): 307-320.
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