Topological characterization of the isomerization mechanisms in XNO (X=H, Cl)

The chemical bond evolution in the isomerization of XNO (X=H, Cl) has been investigated by a topological method based on the Catastrophe Theory. The different domains of structural stability occurring along the reaction path have been identified as well as the bifurcation catastrophes responsible for the changes in the topology of the systems. The covalent isomerization of HNO requires five steps to break the OH bond and form the NH one. The NO subunit is mostly anionic in the transition state. For ClNO, the process involves the chlorine lone pairs. In the transition state NO has a cationic character.