Reduction of ?-Expanded Cyclooctatetraene with Lithium: Stabilization of the Tetra-Anion through Internal Li⁺ Coordination.

ABSTRACT: The chemical reduction of a ?-expanded polycyclic framework comprising a cyclooctatetraene moiety, octaphenyltetrabenzocyclooctatetraene, with lithium metal readily affords the corresponding tetra-anion instead of the expected aromatic dianion. As revealed by X-ray crystallography, the highly contorted tetra-anion is stabilized by coordination of two internally bound Li⁺ , while two external cations remain solvent separated. The variable-temperature ⁷ Li?NMR spectra in THF confirm the presence of three types of Li⁺ ions and clearly differentiate internal binding, consistent with the crystal structure. Density-functional theory calculations suggest that the formation of the highly charged tetra-reduced carbanion is stabilized through Li⁺ coordination under the applied experimental conditions.

SUBMITTER: Zhou Z 

PROVIDER: S-EPMC7898929 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature