Details

Autor(en) / Beteiligte

• Sherborne, Grant J
• Chapman, Michael R
• Blacker, A. John
• Bourne, Richard A
• Chamberlain, Thomas W
• Crossley, Benjamin D
• Lucas, Stephanie J
• McGowan, Patrick C
• Newton, Mark A
• Screen, Thomas E. O
• Thompson, Paul
• Willans, Charlotte E
• Nguyen, Bao N

Titel

Activation and Deactivation of a Robust Immobilized CpIr-Transfer Hydrogenation Catalyst: A Multielement in Situ X‑ray Absorption Spectroscopy Study

Ist Teil von

• Journal of the American Chemical Society, 2015-04, Vol.137 (12), p.4151-4157

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2015

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• A highly robust immobilized [Cp*IrCl2]2 precatalyst on Wang resin for transfer hydrogenation, which can be recycled up to 30 times, was studied using a novel combination of X-ray absorption spectroscopy (XAS) at Ir L3-edge, Cl K-edge, and K K-edge. These culminate in in situ XAS experiments that link structural changes of the Ir complex with its catalytic activity and its deactivation. Mercury poisoning and “hot filtration” experiments ruled out leached Ir as the active catalyst. Spectroscopic evidence indicates the exchange of one chloride ligand with an alkoxide to generate the active precatalyst. The exchange of the second chloride ligand, however, leads to a potassium alkoxide–iridate species as the deactivated form of this immobilized catalyst. These findings could be widely applicable to the many homogeneous transfer hydrogenation catalysts with Cp*IrCl substructure.