ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The McIver-Stanton rules concerning the symmetry of transition states have a counterpart in rules concerning the permutation symmetry of single steps in degenerate rearrangements, derivable with the aid of Longuet-Higgins group theory. The generalized rules are illustrated by the widely studied PX5 polytopal rearrangements. The analysis leads to prediction of hitherto unexplored “pseudorotation” pathways for rearrangements in ethyl and homotetrahedryl cations. CNDO computations of system energies, gradients, and curvatures at critical points on the C2H5+ and C5H5+ surfaces indicate that symmetry-breaking in keeping with the permutation-theoretic predictions is a key feature of the low-energy rearrangements of these systems. In particular, computation indicates that the C2v “classical” homotetrahedral cation corresponds to an energy maximum rather than an energy minimum, or a transition state.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560110304
