All-metal antiaromatic molecule: rectangular Al4(4-) in the Li3Al4(-) anion.

Kuznetsov, Aleksey E; Birch, K Alexander; Boldyrev, Alexander I; Li, Xi; Zhai, Hua-Jin; Wang, Lai-Sheng · Science · 2003

basic_science · Level V

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Abstract

We report the experimental and theoretical characterization of antiaromaticity in an all-metal system, Li3Al4(-), which we produced by laser vaporization and studied with the use of photoelectron spectroscopy and ab initio calculations. The most stable structure of Li3Al4(-) found theoretically contained a rectangular Al4(4-) tetraanion stabilized by the three Li+ ions in a capped octahedral arrangement. Molecular orbital analyses reveal that the rectangular Al4(4-) tetraanion has four pi electrons, consistent with the 4n Hückel rule for antiaromaticity.