Carbonylonium ions: the onium ions of the carbonyl group.

The nomenclature of cations R1C(=O+R3)R2 (R1, R2, R3 = H or organyl) has been examined and shown to be in a state of immeasurable confusion: a pragmatic recommendation is made that the generic term "carbonylonium ions" should be adopted for these intermediates, which comprises the terms "aldehydium" (R1 = H, R2, R3 = H or organyl) and "ketonium ions" (R1, R2 = organyl, R3 = H or organyl) for the corresponding aldehyde- and ketone-based intermediates, respectively.