The free electron laser for infrared experiments (FELIX) at the FOM Institute for Plasma Physics in Nieuwegein, The Netherlands, is capable of delivering a high intensity beam of photons at wavelengths continuously tunable over the mid-IR range, and has allowed unprecedented access to the vibrational spectra of ions isolated and stored in ion-trapping mass spectrometers.  We have used the FELIX facility to generate the first infrared spectra of uranyl complexes in discrete solvation states.  In this study, we extended our initial investigation to include uranyl-anion complexes (hydroxide, methoxide and acetate) that are important to our understanding of the intrinsic interactions between the uranyl ion and bio- and geochemically relevant ligands.  We found that addition of a single hydroxide or methoxide ligand to the uranyl ion weakens the asymmetric UO₂ stretch (a “barometer” used to measure the strength of charge donation from ligand to uranyl ion) to nearly the same extent as 4 neutral acetone or acetonitrile ligands.  The methoxide anion interacts strongly enough to activate the symmetric UO₂ stretch.  A summary of this study, including the influence of the various anions on the asymmetric and symmetric stretching frequencies and a comparison of experimental data to theory, will be presented.