Structure of an unsymmetrical heptalithium cage complex containing aldolate and enolized aldolate dianion

The solid state structure of a lithium mixed anion aggregate, 1, containing aldolate, enolized aldolate, and unenolized ketone, which are all derived from pinacolone, is described. Theoretical calculations (semiempirical PM3 and ab initio HF/6-31G*) are used to quantify the relative stabilities of a model aldolate and also enolized aldolate isomers. Ab initio calculations indicate isomers with a cubane core, for both aldolates and enolized aldolate anions, are stabilized over open ring or ladder derivatives. The highly unsymmetrical structure of 1 incorporates three distinct components, i.e., two bridging monomeric enolized aldolates, an open monomeric enolized aldolate, and a monomeric aldolate. The composition of 1 is consistent with origination from an aldolate tetramer.

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