Ab initio calculations relevant to the mechanism of chemical carcinogenesis by N-nitrosamines. Part 7. The nitrosation of amines by nitrosyl chloride

Ab Initio molecular orbital calculations using split-valence 3-21G and 4-31G basis sets are reported on the formation of ONCl from HONO and HCl and on the formation of H2NNO from NH3 and ONCl. Both minima and transition structures were fully optimized. The energy barriers for both reactions are low, due in part to the flat nature of the potential-energy surfaces, showing that the reactions proceed readily. The calculations show that both reactions may proceed via a low-energy closed shell mechanism without the explicit involvement of water molecules in the transition structure. The calculations also identify the structural features involved in the saddle points for both reactions.