Aldehyde and Ketone Adducts of the Gaseous Trifluoromethyl Cation

IR spectra of CF3+ adduct ions are reported for the first time using infrared multiple photon dissociation (IRMPD). Carbonyl stretches of ketone conjugate acids shift less than do those of ions containing C=OCF3+ groups. Carbonyl absorptions shift in proportion to the empirical softness of the corresponding neutrals. Anharmonic DFT fits band positions of C=OCF3+ stretches for aliphatic ions, but unscaled harmonic calculations match O-CF3 stretches more closely. Calculated O-CF3 bond orders increase with gas phase CF3+ affinities of the corresponding neutral carbonyl.