Ethenium

In chemistry, ethenium, protonated ethylene or ethyl cation is a positive ion with the formula C2H+5.

[1] Another preparation method is to react certain proton donors such as H+3, HeH+, N2H+, and N2OH+ with ethane at ambient temperature and pressures below 1 mmHg.

[1] Contrary to some earlier reports, ethenium was found to be largely unreactive towards neutral methane at ambient temperature and low pressure (on the order of 1 mmHg), even though the reaction yielding sec-C3H+7 and H2 is believed to be exothermic.

Calculations have shown that higher homologues, like the propyl and n-butyl cations also have bridged structures.

Generally speaking, bridging appears to be a common means by which 1° alkyl carbocations achieve additional stabilization.