The silver ion binding energies to alcohols (methanol, ethanol, n-propanol, i-propanol, and n-butanol) and to amides (acetamide, N-methylacetamide, N, N-dimethylacetamide, formamide, N-methylformamide, and N, N-dimethylformamide) have been calculated using density functional theory (DFT) and measured using the threshold collision-induced dissociation (TCID) method. For DFT, the combined basis sets of ECP28MWB for silver and 6-311++G(2df,2pd) for the other atoms were found to be optimal using a series of test calculations on Ag (+) binding to methanol and to formamide. In addition, the Ag (+) binding energies of all ligands were evaluated with nine functionals after full geometric optimizations. TCID binding energies were measured using a triple quadrupole mass spectrometer. Reasonable to good agreements were obtained between the calculated and experimental silver(I) binding energies. Ligation of Ag (+) to the alcohols was primarily via the oxygen, although n-propanol and n-butanol exhibited additional, bidentate coordination via the CH hydrogens. By contrast, silver(I) binding to the amides was all monodentate via the carbonyl oxygen. There appears to be strong correlations between the binding energies and the polarizabilities of the ligands.

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Using competitive threshold collision-induced dissociation (TCID) measurements, experimental bond dissociation energies have been evaluated for the water, methanol, and acetonitrile adducts of silver(I)-amide complexes. The influence of the solvent molecules on the binding energy of silver(I) to acetamide, N-methylacetamide, and N,N-dimethylacetamide was investigated. Experimental results show that solvents decrease the amide binding energy by 4-6 kcal mol(-1). Using density functional theory (DFT), binding energies were evaluated using nine functionals, after full geometry optimizations with the ECP28MWB basis set for silver and the 6-311++G(2df,2pd) basis set for the other atomic constituents of the ligands. In addition, calculations employing the DZVP basis set for Ag and DZVP2 for C, H, N, and O atoms at the B3LYP and MP2 levels of theory were used to investigate the influence of the basis set on the theoretical bond energies. A comparison of the experimental and theoretical silver(I)-ligand bond dissociation energies enables an assessment of the limitations in the basis sets and functionals in describing the energetics of the metal-solvent interaction and the metal-amide interaction. No single functional/basis set combination was found capable of predicting binding energies with a sufficiently high level of accuracy for the silver(I)-amide solvent complexes.

A triple-quadrupole mass spectrometer has been modified for bond-dissociation energy measurements via threshold collision-induced dissociations (TCIDs) by replacing the conventional collision cell with a ring ion guide. Optimal operating conditions for the ring ion guide were determined or derived, and validated using a set of complexes for which bond dissociation energies are known. A comparison with reference data (within a range of 16-57 kcal/mol) indicates an accuracy approaching that of TCID determined on a guided ion-beam mass spectrometer. Complexes for which bond-dissociation energies were measured include metal ion complexes of simple ligands, amino acids and peptides, as well as of carbonic acid. There is excellent agreement between our experimental data and literature data, as well as theoretical data determined using a high-level computational method.