Nature Publishing GroupCorma Canós, A.; Concepción Heydorn, P.; Boronat Zaragoza, M.; Sabater Picot, MJ.; Navas Escrig, J.; Yacaman, MJ.; Larios, E.... (2013). Exceptional oxidation activity with sizecontrolled supported gold clusters of low atomicity. Nature Chemistry. 5 (9) SummaryThe catalyticic activity of gold depends on particle size, with reactivity increasing as particle diameter decreases. Investigation of the trends in the subnanometer regime, where gold exists as small clusters of a few atoms, is now starting thanks to recent advances in synthesis and characterization techniques. An easy method to prepare isolated gold atoms supported on functionalized carbon nanotubes and their performance in the oxidation of thiophenol with O 2 are described. Single gold atoms are not active and they aggregate under reaction conditions into gold clusters of low atomicity, which show a catalytic activity comparable to that sulfhydryl oxidase enzymes. When clusters grow into larger nanoparticles, catalyst activity drops to zero.Theoretical calculations show that gold clusters are able to simultaneously activate thiophenol and O 2 , while larger nanoparticles become passivated by strongly adsorbed thiolates. The combination of an optimum for reactants activation and product desorption makes gold clusters excellent catalysts. Main TextGold has attracted wide interest as catalyst in the last years due to its unexpected activity and, specially, to its high selectivity in organic reactions. [1][2][3] The catalytic properties of gold depend on several factors that in some cases are intimately related:gold particle size and morphology, metal-oxide support interaction, oxidation state of the active sites, etc. 4-8 The influence of particle size has been extensively investigated, and a volcano type curve with a maximum in activity at an optimum diameter has been reported for CO oxidation, 7 alkane oxidation, 9 or propene epoxidation with O 2 and H 2 , 10 while in other cases an exponential increase in activity with decreasing particle size has been observed. 5,11,12 However, the trends in catalytic activity when the particle diameter While it appears that in order to control reactivity, the atomicity control of the gold clusters is crucial, the synthesis of size-selected metal clusters and their deposition over a solid support is a challenging task. 26 The wet-chemistry methods for preparing supported metal clusters involve the anchoring of well defined precursors to an adequate support, 27,28 followed by removal of the ligands by post-synthesis treatments, trying to prevent cluster agglomeration during these steps. 9,[29][30][31]32 Soft landing of monodisperse metal clusters grown in the gas phase and with precise size selection by mass spectrometry is a more straightforward method, but it requires sophisticated equipment, and the scaling up of the process is a major drawback. 20,23,33 In The chemical nature of these isolated atoms has been investigated by X-ray absorption spectroscopy (XAS) and X-ray photoelectron spe...

Transition metal (TM) hydrides display a remarkable range of bonding types, encompassing classical M-H moieties, dihydrogen complexes containing the eta 2-H2 ligand, and trihydrides which display quantum mechanical site exchange. Furthermore, C-H, Si-H and B-H moieties can bind to TM centres in an eta 2-manner, to give sigma-bond complexes with a spectrum of M...H contributions. In addition to these primary bonding modes, TM complexes also indulge in a wide spectrum of hydrogen-bonding interactions, including both M...H-X and the unique type M-H...H-X. This review begins with a historical perspective of the development of TM hydride chemistry, and proceeds to focus on three significant developments of the past two decades: the discovery of sigma-bond and dihydrogen complexes, the involvement of TM hydrides in hydrogen bonding, and the role played by quantum mechanical phenomena in the chemistry and dynamics of TM hydrides. The account concludes with an overview of the inter-relationship between these apparently disparate novel aspects of TM hydride chemistry.

Dynamic observation: The rapid oxidative redispersion of large Pt nanoparticles supported on ceria‐based oxide in autoexhaust catalysts is demonstrated in the absence of Cl by in situ XANES analysis. An atomic migration model accounts for the observed redispersion through the trapping of Pt species at sites on the Ce support that exhibit strong interactions between the Pt oxide and the support.

Reaction of Zn 2+ salts with the terephthalate dianion results in a herringbone motif coordination polymer; the orientation of the terephthalate spacer ligands and the coordination geometry about the Zn 2+ ion is crucially dependent on hydrogen bonding to ancillary ligands; replacement of coordinated water with ethylenediamine results in marked changes to the polymer orientation without disruption of the fundamental features of the material.

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