Molecular wheels on surfaces

Can one have molecules, which are chemisorbed on a surface, but at the same time can exhibit fluxional–rotational motion on the surface and perhaps move on it? We present calculations to show that cyclopentadienyl, adsorbed to Si or Ge surfaces, can exhibit interesting spinning motion. The motion involves movement of the point of attachment around the ring, resulting in a wheel like motion of the molecule, though there is no net motion of the molecule in space. Our studies predict the activation energy for this to be rather low, and hence it should be possible to observe this experimentally.