Mass Spectrometry and Theoretical Chemistry in Service of Catalysis Research: A Ménage-à-Trois at Its Best

The ultimate goal in heterogeneous catalysis is to make use of each and every atom of supported (metal) catalysts, i.e. in the extreme to perform single-atom catalysis (SAC). While this arduous task constitutes a non-trivial, if not daunting challenge in 'real-life' chemistry, in the gas phase SAC can be achieved in a rather straightforward manner by conducting experiments with mass-selected species under (near) single-collision conditions. These mass spectrometry-based studies on isolated reactants, when complemented by state-of-the-art computational and spectroscopic work, provide an ideal arena for probing the energetics and kinetics of a chemical process in an unperturbed environment at a strictly molecular level without being obscured by ill-defined side effects. Thus, the concept of SAC can be explored or, more generally, the mechanisms of reactions and the active parts of single-site catalysts, the so-called 'aristocratic' atoms, can be identified.

Examples discussed include:
(i) The room-temperature, cluster-oxide mediated redox reactions of the CO/N₂O couple which, arguably constitute one of the most prominent oxidation processes, and
(ii) novel metal-mediated C-H bond activation and C-C coupling of methane, which are regarded as one of the holy grails in chemistry.

References:
(1) H. Schwarz, Catal. Sci. Technol. 2017, 7, 4302
(2) H. Schwarz, S. Shaik, J. Li, J. Am. Chem. Soc. 2017, 139, 17201
(3) H. Schwarz, Angew. Chem. Int. Ed. 2011, 51, 1009