A Three-Coordinate Copper(II) Amide from Reductive Cleavage of a Nitrosamine

摘要

Nitrosamines R2N-NO are endogenous species present at submicromolar concentrations in mammalian plasma and tissues. They are similar in physiological abundance and perhaps function as well to S-nitrosothiols RS-NO, which have received a great deal of attention in signaling pathways. For instance, each elicits responses such as vasorelaxation. Nitrosamines may serve as sources of NO~+ as in reversible transnitrosation reactions with thiols to give S-nitrosothiols. In addition, they may serve as donors of the free radical NO, but possess markedly higher R2N-NO homolytic dissociation energies (e.g. Ph2N-NO 87.7 kcal mol~(-1)) than RSNO compounds (RS-NO 20-32 kcal mol~(-1)). Despite their natural occurrence, nitrosamines may be carcinogenic, especially N-alkyl derivatives with α-C-H atoms. Nitrosamines are found in common pollutants such as tobacco smoke, motivating approaches for their passivation which involve the use of Cu-exchanged zeolites to trap and decompose nitrosamines to NO_x.