In-line proximity effects in extended 7-azanorbornanes. 2. a major reduction of N-inversion barriers in symmetrically flanked systems

Dynamic Dynamic (figure presented) oscillation angle decreases as size of sentinel X increases Through-space compression effects from a pair of flanking (sentinel) groups X are shown to cause a flattening of the bridging nitrogen in symmetrically fused 7-azanorbornanes which is evaluated by a substantial reduction of the nitrogen inversion barrier as measured by low-temperature ¹H NMR spectroscopy. This effect is attributed to destabilization of the ground state of the amine.