Re-interpretation of the 2(N+1)2 rule for polyhedral closed-shell π-systems

✍ Scribed by Jun-ichi Aihara

• Book ID: 104108224
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 164 KB
• Volume: 375
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/s0009-2614(03)00914-x

✦ Synopsis

The 2ðN þ 1Þ 2 rule for cage molecules is not always associated with aromaticity. This is due primarily to the fact that this rule does not take into account the arrangement of individual circuits in a polycyclic p-system. Therefore, some polyhedral systems with 2ðN þ 1Þ 2 p-electrons may have negative topological resonance energies (TREs) even if they have large negative nucleus-independent chemical shift (NICS) values at the cage centers. In general, spherical systems with 2ðN þ 1Þ 2 p-electrons do not exhibit marked bond-length alternation even if they are not aromatic at all.