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<jats:title>More alloying on silica</jats:title> <jats:p> Controlling the stoichiometry and achieving a high degree of alloying of metals at ultrasmall scales for catalysis can be difficult. Double complex salts, formed by a cation like Pd(NH <jats:sub>3</jats:sub> ) <jats:sub>4</jats:sub> <jats:sup>2+</jats:sup> and an anion like IrCl <jats:sub>6</jats:sub> <jats:sup>2−</jats:sup> , should be excellent precursors but are poorly soluble and difficult to adsorb directly on metal oxide surfaces. Ding <jats:italic>et al.</jats:italic> show that sequentially adsorbing the cations and anions from organic solvents onto a silica surface, followed by heating in hydrogen, creates well-mixed nanoparticles, most less than 3 nanometers in diameter, for a variety of alloys. These materials were then tested as catalysts for acetylene hydrogenation to ethylene. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6414" page="560" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau4414">560</jats:related-article> </jats:p>

<jats:title>Steps to smaller rings</jats:title> <jats:p> Certain ring-forming reactions in organic chemistry are efficient because the orbital symmetries match up in the reactants and products. Oxyallyl ions tend to react with dienes in this paradigm to form seven-membered rings. Under palladium catalysis, Trost <jats:italic>et al.</jats:italic> redirected this reaction toward more common five-membered tetrahydrofuran rings by appending an ester to the diene. Although that pathway is symmetry-forbidden, the electron-withdrawing ester appears to stabilize a key intermediate along a stepwise route to the smaller ring. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6414" page="564" related-article-type="in-this-issue" vol="362" xlink:href="10.1126/science.aau4821">564</jats:related-article> </jats:p>