Lighter Hydrogenation Catalysts: Enzymes have evolved to use abundant metals such as iron, cobalt, and nickel for redox catalysis. However, synthetic catalysis has generally relied on the rarer, heavier relatives of these elements: ruthenium, rhodium, iridium, palladium, and platinum (see the Perspective by Bullock ). Friedfeld et al. (p. 1076 ) used high-throughput screening to show that the right cobalt precursor can be activated for asymmetric hydrogenation catalysis by using the traditional ligands developed for the precious metals. Zuo et al. (p. 1080 ) focused on iron, demonstrating a highly effective asymmetric transfer hydrogenation catalyst that uses a ligand rationally designed after careful mechanistic study. Jagadeesh et al. (p. 1073 ) prepared supported iron catalysts that selectively reduce nitro substituents on aromatic rings to amines, thereby facilitating the preparation of a wide range of aniline derivatives.

A MOF sets the stage to make amines: Reductive amination is a common method that chemists use to make carbon-nitrogen bonds. The reaction, which often requires precious metal catalysts, couples ammonia or other amines with carbonyl compounds and then with hydrogen. Jagadeesh et al. report a class of nonprecious cobalt nanoparticles that catalyze this reaction across a very broad range of substrates, including complex molecules of pharmaceutical interest (see the Perspective by Chen and Xu). The cobalt was first embedded in a metal-organic framework (MOF), which, upon heating, transformed into a graphitic shell. The catalyst could be conveniently separated from products and recycled up to six times. Science , this issue p. 326 ; see also p. 304

X-ray photoelectron spectroscopy (XPS) investigations of supported nanoparticles smaller than 10 nm show a significant shift of the electron binding energy of core levels compared with the bulk values. In this work, such shifts were examined at differently supported and prepared gold nanoparticles for the 4f electron level. Special attention was paid to the influence of reducing pretreatment in hydrogen and, moreover, the influence of different oxide supports. Surprisingly, in most cases, lower binding energies than the Au 4f_7/2of 84.0 eV were observed depending on the oxidic support as well as the pretreatment conditions. The origin of these differences of the core level values are discussed in terms of different models like electron transfer from the support to the particles, size and geometric effects. It seems that especially geometric factors like the particle shape play an important role.