Structural features of aliphatic N-nitrosamines of 7-azabicyclo[2.2.1]heptanes that facilitate N-NO bond cleavage

N-Nitrosamines can be considered as potential nitric oxide (NO)/nitrosonium ion (NO+) donors. However, the relation of the structures of N-nitrosamine s, in particular of aliphatic N-nitrosamines, to the characteristics of rel ease of NO or NO+ remains unclear. Here we show that aliphatic N-nitrosoami nes of 7-azabicyclo[2.2.1]heptanes can undergo heterolytic N-NO bond cleava ge. On the basis of the observation of reduced rotational barriers of the N -NO bonds in solution and nitrogen-pyramidal structures of the N-nitroso gr oup in the solid state, we postulate that N-NO bond cleavage of N-nitrosami nes is enhanced by a reduction of the resonance in the N-NO group. Computat ional studies suggest that these structural features of the N-nitrosamines of 7-azabicyclo[2.2.1]heptane are derived from angle strain imposed on the CNC angles.