Dissociative electron attachment to 2-chlorotoluene: Unusual temperature effects for the formation of Cl−

•Attachment of low energy electrons to 2-chlorotoluene is followed by dissociation.•The cross-section for the dissociation of Cl– decreases with temperature.•Such negative temperature dependence has only rarely been observed before.•Calculations show a low barrier where neutral and anionic dissociation curves cross.•Therefore non-Arrhenius effects take over and lead to the observed T-dependence.