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Vibrational spectra of a series of gas-phase metal 1+ and 2+ ions solvated by acetone molecules are collected to investigate how the metal charge, number of solvent molecules and nature of the metal affect the acetone. The spectra of Cu+(Ace)(N2)2, Cu+(Ace)4, and M2+(Ace)4, where M = Co, Ni, Cu, and Zn are measured via photodissociation by monitoring fragment ion signal as a function of IR wavenumber. The spectra show a red shift of the C=O stretch and a blue shift of the C–C antisymmetric stretch. DFT calculations are carried out to provide the simulated spectra of possible isomers to be compared with the observed vibrational spectra, and specific structures are proposed. The red shift of the C=O stretch increases as the number of acetone molecules decreases. Higher charge on the metal leads to a larger red shift in the C=O stretch. Although all of the M2+ complexes have very similar red shifts, they are predicted to have different geometries due to their different electron configurations. Unexpectedly, we find that the calculated red shift in the C=O stretch in M+/2+(Ace) is highly linearly correlated with the ionization energy of the metal for a wide range of metal cations and dications. 

We investigate the gas-phase structures and fragmentation chemistry of deprotonated carbohydrate anions using combined tandem mass spectrometry, infrared spectroscopy, regioselective labelling, and theory. Our model system is deprotonated, [lactose-H] − . We computationally characterize the rate-determining barriers to glycosidic bond (C 1 –Z 1 reactions) and cross-ring cleavages, and compare these predictions to our tandem mass spectrometric and infrared spectroscopy data. The glycosidic bond cleavage product data support complex mixtures of anion structures in both the C 1 and Z 1 anion populations. The specific nature of these distributions is predicted to be directly affected by the nature of the anomeric configuration of the precursor anion and the distribution of energies imparted. i.e. , Z 1 anions produced from the β-glucose anomeric form have a differing distribution of product ion structures than do those from the α-glucose anomeric form. The most readily formed Z 1 anions ([1,4-anhydroglucose-H] − structures) are produced from the β-glucose anomers, and do not ring-open and isomerize as the hemiacetal group is no longer present. In contrast the [3,4-anhydroglucose-H] − , Z 1 anion structures, which are most readily produced from α-glucose forms, can ring-open through very low barriers (<25 kJ mol −1 ) to form energetically and entropically favorable aldehyde isomers assigned with a carbonyl stretch at ∼1640 cm −1 . Barriers to interconversion of the pyranose [β-galactose-H] − , C 1 anions to ring-open forms were larger, but still modest (≥51 kJ mol −1 ) consistent with evidence of the presence of both forms in the infrared spectrum. For the cross-ring cleavage 0,2 A 2 anions, ring-opening at the glucose hemiacetal of [lactose-H] − is rate-limiting (>180 (α-), >197 kJ mol −1 (β-anomers)). This finding offers an explanation for the low abundance of these product anions in our tandem mass spectra.