https://doi.org/10.1351/goldbook.P04908
An ion formed by interaction of a molecule with a @P04906@ abstracted from an ion, as often occurs in chemical @I03183@ according to the reaction: \(\text{M}+\text{XH}^{+}\rightarrow \text{MH}^{+}+\text{X}\) . The symbolism [M + H]+ may also be used to represent the protonated molecule. The widely used term 'protonated molecular ion' to describe the MH+ ion is not recommended, since it suggests an associated product of a @P04906@ with a molecular ion.