Noncovalent metal-ligand bond energies as studied by threshold collision-induced dissociation

Abstract

This review focuses on noncovalent metal ion–ligand complexes and measurements of the bond energies of such species. The method utilized in this work is threshold collision‐induced dissociation (CID), as achieved using a guided ion beam tandem mass spectrometer. Accurate determination of bond energies requires attention to many details of the experiments and data analysis. These details are discussed thoroughly and compared to other methods. A comprehensive listing of metal–ligand bond dissociation energies determined by threshold CID is provided. This list includes a variety of metals (alkalis, magnesium, aluminum, and first and second row transition metals), many different types of ligands, and variations in the number of ligands. The trends in these values are discussed, and we elucidate the importance of ion–dipole and ion–induced dipole interactions, chelation, different conformers and tautomers, steric interactions, solvation phenomena, and electronic effects such as hybridization and promotion. © 2000 John Wiley & Sons, Inc., Mass Spec Rev 19: 215–247, 2000

Absolute Potassium Cation Affinities (PCAs) in the Gas Phase

“…This suggests that the destabilizing effect of ligand deformation plays an important role in determining the PCA of multidentate complexes. [3,7,46] Ethers and dioxanes: For this class of ligands, K binds to the oxygen atom with a typical K ¥¥¥ O distance of 2.65 ä, slightly longer than that found in K complexes of aliphatic alcohols, and hence the PCA is smaller than that of the corresponding alcohol analogue.…”

“…[7,10,24,26,27,32,33] In many instances, reliable theoretical results have been shown to provide a complementary/alternative route for obtaining and confirming alkali metal cation affinities. [9, 34±37] Also, theoretical findings on the most stable and low-lying binding modes/structures often provide new insights into the interpretation of experimental data.…”

“…While the experimental K affinities for He and Ne are not known, the Ar affinity [4] was determined to be 14 (7) kJ mol À1 at 0 K (experimental uncertainty in parenthesis). Our calculated K affinity for Ar (8 kJ mol À1 at 0 K) is within the error limit of this experimental value.…”

Temperature effects on prevalent structures of hydrated Fe+ complexes: Infrared spectroscopy and DFT calculations of Fe+(H2O)n (n = 3–8)

“…Although the common oxidation states of many transition metals (M) are usually higher than +1 in condensed phases, complexes of singly charged M + ions and small molecules have been the focus of numerous studies in the gas phase. [1][2][3][4][5][6] Gas-phase studies of hydrated metal ions have offered a unique opportunity to gain insight into ion solvation at the microscopic level. High-pressure mass spectrometry 1 and collision-induced dissociation (CID) technique 2 In the experimental measurement of D n , the M + (H 2 O) n ions were generated under thermal equilibrium conditions at a room temperature.…”

Collision-induced dissociation studies of FemOn+ : Bond energies in small iron oxide cluster cations, FemOn+ (m=1–3, n=1–6)

“…The CID method has proven to be an effective means of determining bond energies for a wide range of ionized molecules, complexes, and clusters. [35][36][37] The present work provides fundamental thermochemistry for a variety of iron oxide cluster cations and is an imperative precursor for quantitative studies of the chemical reactivity of such species.…”