ABSTRACTIon pair complexes of triethylammonium, [(CH2CH3)3NH]+, and (X = F, Cl) are studied with a combination of infrared multiple photon dissociation (IRMPD) action spectroscopy and density functional theory calculations. IRMPD spectra show that the charge-carrying proton is oriented towards a trigonal face of the halogenated closo-dodecaborate in both derivatives. Resonant IR absorption via or [(CH2CH3)3NH]+ bands in the 800–1600 cm−1 region drives dissociation via the lowest energy proton-transfer fragmentation channel and the charge transfer (i.e. redox) threshold, which is second lowest in energy. By tuning the power of the interrogating laser or the wavenumber (to select specific vibrational transitions), one can control the degree of fragmentation via the two lowest energy dissociation thresholds.