Catalysts based on single atoms of scarce precious metals can lead to more efficient use through enhanced reactivity and selectivity. However, single atoms on catalyst supports can be mobile and aggregate into nanoparticles when heated at elevated temperatures. High temperatures are detrimental to catalyst performance unless these mobile atoms can be trapped. We used ceria powders having similar surface areas but different exposed surface facets. When mixed with a platinum/aluminum oxide catalyst and aged in air at 800°C, the platinum transferred to the ceria and was trapped. Polyhedral ceria and nanorods were more effective than ceria cubes at anchoring the platinum. Performing synthesis at high temperatures ensures that only the most stable binding sites are occupied, yielding a sinter-resistant, atomically dispersed catalyst.

Vol. 76 ether layer was separated and the aqueous layer extracted with 6 portions of 25 ml. of ether. Removal of the solvent after drying gave a residue which was distilled to give a yellow liquid, b.p. 102-105°(4.5 mm.), 3.5 g. (20%). A large tarry residue was left in the distilling flask. Redistillation gave 3.0 g. (17%), n26D 1.5122, d2i. 0.9646, of 2-Ndimethylammo-4-butylpyrimidine. On standing in a closed flask for 24 hours this compound turns red.

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Die Chloro‐chlorvinyl‐Pt(II)‐ und ‐Pd(II)‐Komplexe (I) werden ebenso wie die Bromo‐bromvinyl‐Pt(II)‐Analogen(V) durch Umsetzung der Tetrakjs‐[phosphinl‐metall(0)‐Komplexe (III) mit den entsprechenden Halogenäthylenen (II) oder (IV) dar.