allyl cation

https://doi.org/10.1351/goldbook.12331
Even-electron ion formulated as \(\ce{R^{1}R^{2}C=CR^{3}C+R^{4}R^{5}}\) and its resonance forms.
Source:
PAC, 2013, 85, 1515. (Definitions of terms relating to mass spectrometry (IUPAC Recommendations 2013)) on page 1521 [Terms] [Paper]