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

• Published in: Angewandte Chemie International Edition 2005-04, Vol.44 (16), p.2336-2354
• Main Authors: Böhme, Diethard K., Schwarz, Helmut
• Format: Article
• Language: English
• Subjects: bond activation; catalysis; cluster compounds; elementary processes; mass spectrometry
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.200461698

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. Not just hot air: Complete catalytic cycles under strictly thermal conditions can be studied by means of modern mass spectrometry, and the underlying elementary processes have been uncovered (see picture for the Fe+‐mediated oxidation of methane by molecular oxygen, with methanol as a catalytic co‐reductant). Examples cover aspects of catalysis pertinent to areas as diverse as atmospheric chemistry and surface chemistry.