Catalytic water oxidation has been investigated using five iridium complexes as precatalysts and NaIO4 as an oxidant at various pH conditions. An increase in the activity of all complexes was observed with increasing pH. A detailed analysis of spectroscopic data together with O2-evolution experiments using Cp*Ir(6,6′-dihydroxy-2,2′-bipyridine)(OH2)(2+) as a precatalyst indicate that the high ca...

A series of Cp*IrIII dimers have been synthesized to elucidate the mechanistic viability of radical oxo-coupling pathways in iridium-catalyzed O2 evolution. The oxidative stability of the precursors toward nanoparticle formation and their oxygen evolution activity have been investigated and compared to suitable monomeric analogues. We found that precursors bearing monodentate NHC ligands degrad...

We present the atomic structure of Ir nanoparticles with 1.5 nm diameter at half height and three layers average height grown on graphene/Ir(111). Using surface x-ray diffraction, we demonstrate that Ir nanoparticles on graphene/Ir(111) form a crystallographic superlattice with high perfection. The superlattice arrangement allows us to obtain detailed information on the atomic structure of the ...

Iridium nanoparticles have only been reported with roughly spherical shapes and sizes of 1-5 nm, making it impossible to investigate their facet-dependent catalytic properties. Here we report for the first time a simple method based on seed-mediated growth for the facile synthesis of Ir nanocrystals with well-controlled facets. The essence of this approach is to coat an ultrathin conformal shel...

Pairwise and random addition processes are ordinarily indistinguishable in hydrogenation reactions. The distinction becomes important only when the fate of spin correlation matters, such as in parahydrogen-induced polarization (PHIP). Supported metal catalysts were not expected to yield PHIP signals given the rapid diffusion of H atoms on the catalyst surface and in view of the sequential stepw...

Aminocarboxylic acids, such as 2-aminobenzoic acid, react easily with [Ir(COD)(PMe3)3]Cl, (COD=1,5-cyclooctadiene), in THF to produce hydridoaminocarboxylato iridium(III) complexes in high yields. These octahedral complexes are formed via oxidative addition reaction of the O-H bond of the carboxylic group with the central metal. The starting iridium(I) complex losses t...

A thermally and air stable O-donor, iridium-methoxo complex is reported that undergoes stoichiometric, intermolecular C-H activation of benzene with co-generation of methanol and the iridium-phenyl complex.

Nanocomposites of iridium nanoparticles (Ir NPs), supported on graphene nanosheets, are synthesized and their electrocatalytic acitivities in the oxygen reduction reaction (ORR) are studied depending on their Ir oxidation state. Graphene functionalized with poly(vinyl pyrrolidone) (pRGO) is a suitable support for Ir NPs, producing well-monodispersed Ir NPs anchored strongly on the pRGO surface ...