Observation of All-Metal Aromatic Molecules
Abstract
Aromaticity is a concept invented to account for the unusual stability of an important class of organic molecules: the aromatic compounds. Here we report experimental and theoretical evidence of aromaticity in all-metal systems. A series of bimetallic clusters with chemical composition MAl4<SUP ARRANGE="STAGGER">- (M = Li, Na, or Cu), was created and studied with photoelectron spectroscopy and ab initio calculations. All the MAl4<SUP ARRANGE="STAGGER">- species possess a pyramidal structure containing an M+ cation interacting with a square Al4<SUP ARRANGE="STAGGER">2- unit. Ab initio studies indicate that Al4<SUP ARRANGE="STAGGER">2- exhibits characteristics of aromaticity with two delocalized π electrons (thus following the 4n + 2 electron counting rule) and a square planar structure and maintains its structural and electronic features in all the MAl4<SUP ARRANGE="STAGGER">- complexes. These findings expand the aromaticity concept into the arena of all-metal species.
- Publication:
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Science
- Pub Date:
- February 2001
- DOI:
- 10.1126/science.291.5505.859
- Bibcode:
- 2001Sci...291..859L
- Keywords:
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- CHEMISTRY