Carbonylonium ions: the onium ions of the carbonyl group.

The nomenclature of cations RC(=OR)R (R, R, R = 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" (R = H, R, R = H or organyl) and "ketonium ions" (R, R = organyl, R = H or organyl) for the corresponding aldehyde- and ketone-based intermediates, respectively.