All-Metal Antiaromatic Molecule: Rectangular Al₄⁴⁻ in the Li₃Al₄⁻ Anion

• Published in: Science (American Association for the Advancement of Science) Vol. 300; no. 5619; pp. 622 - 625
• Main Authors: Kuznetsov, Aleksey E., Birch, K. Alexander, Boldyrev, Alexander I., Li, Xi, Zhai, Hua-Jin, Wang, Lai-Sheng
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 25.04.2003
• Subjects: Ab initio calculations; Alloys; Anions; Atomic and molecular physics; Atoms; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Chemical bonding; Electronic structure of atoms, molecules and their ions: theory; Electrons; Exact sciences and technology; Isomers; Lasers; Molecular properties and interactions with photons; Molecules; Photoelectron spectra; Photoelectron spectroscopy; Photoelectrons; Physics; Ultraviolet and vacuum ultraviolet photoelectron spectra; Aluminium Molecular ions; Inorganic compounds; Frontier orbital; Molecular structure; Aluminium compounds; Bond angle; Theoretical study; Experimental study; Lithium compounds; Bond lengths; Polyatomic molecules; Electron binding energy; Negative ions; Inorganic anion; Multicharged ions; Ultraviolet photoelectron spectra; Ab initio calculations
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1082477

We report the experimental and theoretical characterization of antiaromaticity in an all-metal system,$Li_{3}Al_{4}^{-}$, which we produced by laser vaporization and studied with the use of photoelectron spectroscopy and ab initio calculations. The most stable structure of$Li_{3}Al_{4}^{-}$found theoretically contained a rectangular$Al_{4}^{4-}$tetraanion stabilized by the three Li+ions in a capped octahedral arrangement. Molecular orbital analyses reveal that the rectangular$Al_{4}^{4-}$tetraanion has four π electrons, consistent with the 4n$H\ddot{u}ckel$rule for antiaromaticity.