Photolytic water oxidation catalyzed by a molecular carbene iridium complex

By Petronilho, Ana; Rahman, Mahfujur; Woods, James A.; Al-Sayyed, Haris; Muller-Bunz, Helge; Don MacElroy, J. M.; Bernhard, Stefan & Albrecht, Martin
Published in Dalton Trans. The Royal Society of Chemistry 2012

Abstract

The complex IrCl2(Cp*)(trz) (trz = triazolylidene), 2, was prepared from readily available 1, 3-dimethyl-4-phenyl-1, 2, 3-triazolium salt. Under basic conditions, the C-bound phenyl group readily cyclometalates, while under acidic conditions, cyclometalation is reversed. The sensitivity of the Caryl-Ir bond but not the Ctrz-Ir bond towards acidolysis provided a basis for using 2 as a catalyst in CeIV-mediated water oxidation. The catalytic activity is characterized by a robust catalytic cycle, affording excellent turnover numbers (TON > 20 000). Under cerium-free conditions and in the presence of hematite as a photoelectrode, light-induced activity was observed. The photoelectrochemical reaction is strongly pH-dependent, which requires pH adjustments when running multiple cycle experiments to regenerate the catalytic activity. Analogous chelating complexes display better stability and higher catalytic activity than the monodentate complex 2.

Read Article » Back