Metal complexes as promoters of N-nitrosation reactions: a progress report

Our research on three classes of transition metal-containing N-nitrosating agents is described. One class, the nitrito complexes, can give rise in organic solvents to quantitative yields of N-nitrosamines on exposure to secondary amines. The second class is capable of activating nitrite as an N-nitrosating agent in aqueous alkaline media; it involves N-coordination of nitrite, followed by removal of oxide ion to form the active metal nitrosyl species. The third class of N-nitrosating agent involves an as yet incompletely characterized metal complex containing a ligand having the formula NO3. The possible significance of compounds in these classes in environmental or in vivo N-nitrosamine formation is discussed.