Can an eight π-electron bare ring be planar?

Phys Chem Chem Phys. 2011 Dec 14;13(46):20615-9. doi: 10.1039/c1cp22415h. Epub 2011 Sep 9.

Abstract

Here we explore in silico an alternative to make planar eight π-electron bare ring systems with substitutions of some cyclooctatetraene ring carbon atoms by heavier group 14 elements. We found that the most stable eight membered rings with formulae C(4)Si(4)H(8), C(4)Ge(4)H(8), and C(4)Sn(4)H(8) have a perfect planar structure, enhancing delocalization energy as compared to cot.