Issue 6, 2019

Molecular water oxidation catalysis by zwitterionic carboxylate bridge-functionalized bis-NHC iridium complexes

Abstract

Zwitterionic water-soluble [Cp*IrIIICl{(MeIm)2CHCOO}] and [IrI(cod){(MeIm)2CHCOO}] complexes featuring a carboxylate bridge-functionalized bis-N-heterocyclic carbene ligand efficiently catalyzed water oxidation using ammonium cerium(IV) nitrate (CAN) or sodium periodate as sacrificial oxidants. Excellent yields with TOF50 numbers up to 1000 h−1 have been achieved using CAN as electron acceptor at [CAN]/[Ir] ratios higher than 700. The investigation of the reaction mechanism by UV-vis seems to evidence that both catalyst precursors are transformed into the same active molecular species resulting from the degradation of the hydrocarbon ligands which is partially supported by the similarity of the oxygen evolution profiles at moderate oxidant/catalyst ratios for both catalyst precursors and the same chemical oxidant. In addition, DLS studies provide evidence for the participation of homogeneous iridium molecular species as intermediates likely stabilized by the carboxylate-functionalized bis-NHC ligand.

Graphical abstract: Molecular water oxidation catalysis by zwitterionic carboxylate bridge-functionalized bis-NHC iridium complexes

Supplementary files

Article information

Article type
Paper
Submitted
07 Nov 2018
Accepted
21 Feb 2019
First published
22 Feb 2019
This article is Open Access
Creative Commons BY-NC license

Catal. Sci. Technol., 2019,9, 1437-1450

Molecular water oxidation catalysis by zwitterionic carboxylate bridge-functionalized bis-NHC iridium complexes

R. Puerta-Oteo, M. V. Jiménez and J. J. Pérez-Torrente, Catal. Sci. Technol., 2019, 9, 1437 DOI: 10.1039/C8CY02306A

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