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

Journal of Organometallic Chemistry Elsevier

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.

Authors with CRIS profile

Nicolaas van Eikema Hommes Computer-Chemie-Centrum (CCC) Paul Schleyer Naturwissenschaftliche Fakultät

Involved external institutions

University of California Los Angeles (UCLA) US United States (USA) (US)

How to cite

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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