Antiaromaticity in bare deltahedral silicon clusters satisfying Wade's and Hirsch's rules: an apparent correlation of antiaromaticity with high symmetry.

Entirely unlike the aromatic closo BnHn2- borane dianions, isoelectronic Si62- and Si122- are antiaromatic. Their Oh and Ih symmetries are responsible, as the other deltahedral silicon dianion clusters do not exhibit this behavior. These high symmetries prevent mixing among the degenerate lone pair and skeletal orbitals, leading to paratropic behavior.