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series 1

2-nor­bornyl cat­ion

Other names: 2-bi­cyclo­[2.2.1]­heptyl cation


21/50 common

2-norbornyl refers to a specific cation of the simple bicyclic organic molecule norbornane. This species was the subject of a decades-long feud in the chemical literature stretching back to the year 1949 whose contours at times proved so vitriolic that entire articles were written on the subject from the mediating perspective of an "innocent bystander". The subject of the debate relates to the fundamental nature of multiple resonance states such as benzene. Such molecules display structural characteristics akin to a weighted average of their individual resonance contributors. However, for much of chemical history it was unclear whether, at the atomic level, molecules actually "jumped between" individual resonance structures at incredible speed (the so-called "classical depiction") or if the delocalized weighted average of the theoretical resonance contributors (the "non-classical depiction") was itself somehow the true state of the species. 2-norbornyl is noteworthy because it was the first chemical species for which researchers were able to demonstrate empirically (by spectroscopic, computational, and crystallographic means) that the delocalized non-classical picture of 2-norbornyl (depicted here) was in fact the true ground state of the cation. This seemingly trivial observation in fact reveals something deeply insightful (and, some might say, unnerving) about the fundamentally quantum nature of reality.