Gas‐Phase Catalysis by Atomic and Cluster Metal Ions: The Ultimate Single‐Site Catalysts

Abstract

Gas-phase experiments with state-of-the-art techniques of mass spectrometry provide detailed insights into numerous elementary processes. The focus of this Review is on elementary reactions of ions that achieve complete catalytic cycles under thermal conditions. The examples chosen cover aspects of catalysis pertinent to areas as diverse as atmospheric chemistry and surface chemistry. We describe how transfer of oxygen atoms, bond activation, and coupling of fragments can be mediated by atomic or cluster metal ions. In some cases truly unexpected analogies of the idealized gas-phase ion catalysis can be drawn with related chemical transformations in solution or the solid state, and so improve our understanding of the intrinsic operation of a practical catalyst at a strictly molecular level.

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

“…11 Gas-phase and theoretical studies can be used as a helpful tool to gain complementary insights into the molecular mechanism and intrinsic reactivity, as well as to provide an ideal field for detailed experiments of the energetic and kinetics of any bond-making and bond-breaking process at molecular level. 12 In this sense, the theoretical works can provide a deeper insight into the principles governing the reactions of transition metal oxides.…”

Protonated nitro group as a gas-phase electrophile: Experimental and theoretical study of the cyclization of o-nitrodiphenyl ethers, amines, and sulfides

“…Additionally, we seek to determine the mechanisms under solvent-free conditions because the mechanisms of these reactions are not well known. Investigations in the absence of solvent employ ideal conditions for understanding energetics and intrinsic mechanisms of reactions at the molecular level [6,7]. Fast atom bombardment (FAB), chemical ionization (CI) and electrospray ionization (ESI) readily generate protonated molecules or [M + H] + ions, and well established mass spectrometric methods for ion chemistry, reveal the properties of and the mechanisms for the reactions of protonated molecules in the absence of a solvent.…”

Cluster reactivity experiments: Employing mass spectrometry to investigate the molecular level details of catalytic oxidation reactions

“…A particularly fruitful area of cluster research that depends entirely on mass spectrometry is the application of gas-phase clusters to model the reactions taking place on the surface of heterogeneous catalysts (35,36). Gas-phase cluster experiments allow the fundamental reactive behavior of catalytic materials to be studied in an environment that avoids the complications present in condensed-phase research (36).…”

“…Gas-phase cluster experiments allow the fundamental reactive behavior of catalytic materials to be studied in an environment that avoids the complications present in condensed-phase research (36). Furthermore, massselected cluster studies, employing tandem mass spectrometry, enable the influence of factors such as size, stoichiometry, and ionic charge state on cluster reactivity to be determined with atomic-level precision (35).…”