Non-classical Ion - Other Non-classical Ions

Other Non-classical Ions

The simplest two-carbon carbonium ions are protonated acetylene (ethynium, C₂H+
3), protonated ethylene (ethenium, C₂H+
5), and protonated ethane (ethanium, C₂H+
7). Their formulas were explained either as a "classical" structure, with one pentavalent carbon bearing a +1 charge, and a "non-classical" structure in which the +1 charge and the extra valence are spread over the two carbons, with the extra hydrogen bridging between them. Infrared spectroscopy eventually established that both structures are stable, the non-classical one slightly more so.