Controlling the size and uniformity of metal clusters with atomic precision is essential for fine-tuning their catalytic properties, however for clusters depositedo ns upports, such controli sc hallenging. Here, by combining X-ray absorption spectroscopy and density functional theory calculations, it is shown that supports play ac rucial role in the evolution of monolayer-protected clusters into catalysts. Based on the acidic nature of the support, cluster-support interactions lead either to fragmentation of the cluster into isolatedA u-ligand species or ligand-free metallic Au 0 clusters. On Lewis acidic supportst hat bind metals strongly,t he latter transformation occurs whilep reserving the original size of the metal cluster, as demonstrated for various Au n sizes. These findings underline the role of the support in the designo fs upported catalysts and represent an important step toward the synthesis of atomically precise supported nanomaterials with tailoredp hysico-chemical properties.

The reaction of the intramolecular frustrated Lewis pair (FLP) tBu2PCH2BPh2 with the amine‐boranes NH3·BH3 and Me2NH·BH3 leads to the formation of the corresponding FLP‐H2 adducts as well as novel five‐membered heterocycles that result from capturing the in situ formed amino‐borane by a second equivalent of FLP. The sterically more demanding tBu2PCH2BMes2 does not form such a five‐membered heterocycle when reacted with Me2NH·BH3 and its H2 adduct liberates dihydrogen at elevated temperatures, promoting the metal‐free catalytic dehydrogenation of amine‐boranes.

Supported nanoparticulate Au/Ti-SiO2 catalysts are a promising candidate for selective epoxidation of propene with H2/O2 mixtures. Here, we demonstrate that by altering the acidity of the surface titanol groups in Au/Ti-SiO2, the selectivity of these catalysts in propene oxidation can be controlled. That is, Au/Ti-SiO2 prepared using an alkali base during gold deposition shows basic properties due to the formation of Ti-ONa groups. The catalysts that contained Na+ and neutralized acid sites demonstrate high selectivity toward propene oxide. On the contrary, when the acidity of the Ti-OH groups is preserved by using NH4OH as a base during gold deposition, the catalyst is highly selective toward propanal at a similar propene conversion. This difference in selectivity is explained by the isomerization of initially formed propene oxide into propanal over acidic Ti-OH groups as we demonstrated using stacked bed experiments, where the Ti-support was exposed to propene oxide. When Na+ was present, no isomerization was observed, while without Na+ present, propene oxide was isomerized to propanal. In short, we demonstrate the crucial role of Na+ and acidic Ti-sites in steering the selectivity in gold-catalyzed propene epoxidation.

The epoxidation of propene without forming a substantial amount of byproducts is one of the holy grails of catalysis. Supported Cu, Ag and Au catalysts are studied for this reaction and the activity of the supported metals is generally well understood. On the contrary, limited information is available on the influence of the support on the epoxide selectivity. The reaction of propene with equal amounts of hydrogen and oxygen was tested over gold nanoparticles deposited onto CeO2, TiO2, WO3, γ-Al2O3, SiO2, TiO2-SiO2 and titanosilicate-1. Several metal oxide supports caused further conversion of the synthesized propene oxide. Strongly acidic supports, such as WO3 and titanosilicate-1, catalyzed the isomerization of propene oxide towards propanal and acetone. Key factors for achieving high PO selectivity are having inert or neutralized surface sites, a low specific surface and/or a low density of surface -OH groups. This work provides insights and practical guidelines to which metal oxide support properties lead to which products in the reaction of propene in the presence of oxygen and hydrogen over supported gold catalysts.

For mixed MoW carbide catalysts, the relationship between synthesis conditions, evolution of (mixed) phases, extent of mixing, and catalytic performance of supported Mo/W carbides remains unclear. In this study, we prepared a series of carbon nanofibersupported mixed Mo/W-carbide catalysts with varying Mo and W compositions using either temperature-programmed reduction (TPR) or carbothermal reduction (CR). Regardless of the synthesis method, all bimetallic catalysts (Mo:W bulk ratios of 1:3, 1:1, and 3:1) were mixed at the nanoscale, although the Mo/W ratio in individual nanoparticles varied from the expected bulk values. Moreover, the crystal structures of the produced phases and nanoparticle sizes differed depending on the synthesis method. When using the TPR method, a cubic carbide (MeC 1−x ) phase with 3−4 nm nanoparticles was obtained, while a hexagonal phase (Me 2 C) with 4−5 nm nanoparticles was found when using the CR method. The TPR-synthesized carbides exhibited higher activity for the hydrodeoxygenation of fatty acids, tentatively attributed to a combination of crystal structure and particle size.

The fate of phosphine‐protected gold clusters is shown to be determined by the surface acidity of the oxide support they are deposited on. Using X‐ray absorption spectroscopy and density functional theory computations, this work shows that, independent of the size of the cluster, on Brønsted acid supports, it completely disintegrates into gold‐phosphine complexes, whereas on Lewis acid supports, the ligands peel away leaving behind the metallic gold cluster. More information can be found in the Full Paper by A. Longo, H. Häkkinen, B. Donoeva, et al. on page 7051.