Exploring the Gas‐Phase Formation and Chemical Reactivity of Highly Reduced M8L6 Coordination Cages. Issue 45 (7th October 2022)

• Record Type: Journal Article
• Authors: Pfrunder, Michael C.; Marshall, David L.; Poad, Berwyck L. J.; Stovell, Ethan G.; Loomans, Benjamin I.; Blinco, James P.; Blanksby, Stephen J.; McMurtrie, John C.; Mullen, Kathleen M.
• Is Part Of: Angewandte Chemie international edition. Volume 61:Issue 45(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-10-07
• Subjects: Coordination Cage -- Electron Transfer -- Low Oxidation State Transition Metals -- Mass Spectrometry -- Supramolecular; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202212710
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Coordination cages with well‐defined cavities show great promise in the field of catalysis on account of their unique combination of molecular confinement effects and transition‐metal redox chemistry. Here, three coordination cages are reduced from their native 16 + oxidation state to the 2 + state in the gas phase without observable structural degradation. Using this method, the reaction rate constants for each reduction step were determined, with no noticeable differences arising following either the incorporation of a C60 ‐fullerene guest or alteration of the cage chemical structure. The reactivity of highly reduced cage species toward molecular oxygen is "switched‐on" after a threshold number of reduction steps, which is influenced by guest molecules and the structure of cage components. These new experimental approaches provide a unique window to explore the chemistry of highly‐reduced cage species that can be modulated by altering their structures and encapsulated guest species. Abstract : Coordination cages containing porphyrin subunits are reduced up to fourteen times in the gas phase. While the presence or absence of Nickel(II) coordinated in the porphyrin binding site does not affect the rate of reduction, the reactivity of the reduced species toward molecular O2 is significantly enhanced in the former case. Additionally, the presence of a C60 fullerene guest within the nickelated cage reduces its reactivity.