Structure of the Observable Histidine Radical Cation in the Gas Phase: A Captodative α‐Radical Ion

Abstract

The observable histidine radical cation generated by collision-induced dissociation of the [CuII(2,2′:6′,2′′-terpyridine)(His)].2+ complex carries the positive charge on the protonated imidazole ring and the radical formally on the α carbon. This structure has been confirmed by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional calculations.