Do all-metal antiaromatic clusters exist?
As shown by detailed nucleus-independent chemical shift (NICS) analyses of the contributions of each molecular orbital, the very recently reported gas-phase all-metal Al4Li3- anion and its relatives (Kuznetsov, A.E.; Birch, K.A.; Boldyrev, A.I.; Li, X.; Zhai, A.I.; Wang, L.S. Science 2003, 300, 622) are aromatic rather than antiaromatic. The paratropic (antiaromatic) four-pi-electron contribution is overcome by the predominating diatropic effects of sigma aromaticity. However, true antiaromatic all-metal clusters, such as Sn62- (Schiemenz, B.; Huttner, G. Angew. Chem., Int. Ed. Engl. 1993, 32, 297), do exist.
Chen
Zhongfang
Z
Department of Chemistry and Center for Computational Quantum Chemistry, University of Georgia, Athens, GA 30602, USA.
Corminboeuf
Clémence
C
Heine
Thomas
T
Bohmann
Jon
J
Schleyer
Paul von Ragué
Pv