Adsorbed hypostrophene: can it roll on a surface by rearrangement of bonds?

Abstract

Hypostrophene is well-known to undergo the degenerate Cope rearrangement. Our calculations show that hypostrophene chemisorbed on the Al(1 0 0) surface can undergo a similar rearrangement involving only single bonds, resulting in a net movement of the molecule on the surface. The activation energy is found to be 16.9 kcal/mol. The usual diffusional (sliding) motion is found to have activation energy about five times larger. Degenerate Cope rearrangement of free hypostrophene has a barrier of 25.3 kcal/mol and the metal decreases this value, even though the adsorbed molecule has no double bonds in it.