Prismanes

The prismanes are a class of hydrocarbon compounds consisting of prism-like polyhedra of various numbers of sides on the polygonal base.

Chemically, it is a series of fused cyclobutane rings (a ladderane, with all-cis/all-syn geometry) that wraps around to join its ends and form a band, with cycloalkane edges.

As n becomes increasingly large, however, modeling experiments find that highly symmetric geometry is no longer stable, and the molecule distorts into less-symmetric forms.

One series of modelling experiments found that starting with [11]prismane, the regular-prism form is not a stable geometry.

[6] The carbons at each intermediate level—the n-gon bases where the prismanes fuse to each other—have no hydrogen atoms attached to them.