Symmetry of nonrigid molecules and isomerization processes

Abstract

AbstractStarting from the concept of a totally flexible molecule, rigidity is introduced by restricting progressively the allowed permutations. Each nonrigid isomer is then characterized by its Longuet‐Higgins group ℒ of allowed permutation inversions. For a given ℒ all nonrigidity types correspond to all possible choices of the symmetry subgroup ℒ of the skeleton. The structure of ℒ also allows a characterization of the isomerization processes studied in chemical kinetics. In both situations, isomerization mechanisms may be associated with generators and are, in the simplest situations, represented by Cayley graphs.