Radical ion

A radical ion is a free radical species that carries a charge. Radical ions are encountered in organic chemistry as reactive intermediates and in mass spectrometry as gas phase ions. Positive radical ions are called radical cations whereas negative radical ions are called radical anions.

In organic chemistry, a radical ion is typically indicated by a superscript dot followed by the sign of the charge: ${\displaystyle M^{\bullet +}}$ and ${\displaystyle M^{\bullet -}}$. In mass spectrometry, the sign is written first, followed by the superscripted dot: ${\displaystyle M^{+\bullet }}$ and ${\displaystyle M^{-\bullet }}$.

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