Should bond-formation lag behind bond-cleavage in radical-exchange reactions

摘要

A few simple concerted radical-exchange reactions (A + BC -> AB + C) are examined by the quantum-mechanical ab initio methods via calculations of bond orders and energies. Results reveal that, during these reactions, a small free valence develops on the migrating atom. As a result, the degree of bond-cleavage is more advanced than that of bond-formation with a common migrating atom at the transition state. The fact that bond-formation lags behind bond-cleavage is also examined by the configuration mixing of the reactant configurations at the early stages of the reaction.