The walk rearrangement of cyclopentadienylphosphanes and related compounds is analyzed on the basis of a quantum chemical study. Although according to orbital symmetry considerations the reaction takes place with retention of configuration (at the migrating atom), inversion of configuration is also feasible. Low energy barriers for the walk reaction are expected if (a) radical stabilizing groups are attached to the cyclopentadienyl unit, (b) the fragment MR2 (migrating group) exerts strong radical stabilizing ability and (c) possesses energetically high lying frontier orbitals. The final goal, the device of a molecular structure which freezes in the transition state structure is discussed