Abstract
Fourteen Cp*IrIII complexes, bearing various combinations of N- and C-spectator ligands, are assayed in hydrogen-transfer catalysis from isopropyl alcohol to acetophenone under various conditions to investigate ligand effects in this widely used reaction. The new cationic complexes bearing monodentate pyridine and N-heterocyclic carbene (NHC) ligands were characterized crystallographically and by variable-temperature nuclear magnetic resonance (VT-NMR). Control experiments and mercury poisoning tests showed that iridium(0) nanoparticles, although active in the reaction, are not responsible for the high activity observed for the most active precatalyst [Cp*Ir(IMe)2Cl]BF4 (6). For efficient catalysis, it was found necessary to have both NHCs in monodentate form; tying them together in a bis-NHC chelate ligand gave greatly reduced activity. The kinetics of the base-assisted reaction showed induction periods as well as deactivation processes, and H/D scrambling experiments cast some doubt on the classical monohydride mechanism.
Original language | English |
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Pages (from-to) | 99-108 |
Number of pages | 10 |
Journal | ACS Catalysis |
Volume | 4 |
Issue number | 1 |
Early online date | 9 Dec 2013 |
DOIs | |
Publication status | Published - 3 Jan 2014 |
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Ulrich Hintermair
- Department of Chemistry - Royal Society University Research Fellow & Reader
- Centre for Sustainable Chemical Technologies (CSCT)
- Made Smarter Innovation: Centre for People-Led Digitalisation
- Institute of Sustainability and Climate Change
Person: Research & Teaching, Core staff, Researcher