Selective Stereochemical Catalysis Controlled by Specific Atomic Arrangement of Ordered Alloys

Abstract

AbstractUnprecedented surface stereochemistry governed by specific atomic arrangement of intermetallic compounds (ordered alloys) is shown. Hydrogen‐mediated cis–trans alkene isomerization is selectively catalyzed without overhydrogenation to alkanes by Rh‐based intermetallic compounds displaying an orthorhombic Pnma structure such as RhSb. Multiple characterization techniques combined with DFT calculations revealed that (2 1 1), (0 2 0), and (0 1 3) planes comprising one‐dimensionally aligned Rh rows separated by Sb atoms (1D‐planes) dominated RhSb surfaces. Systematic DFT calculations indicated that geometric constraints of these 1D‐planes and steric hindrance from one alkyl group of cis‐alkene limited hydrogen access to the alkenyl carbon to one direction, enabling one‐atom hydrogenation for isomerization, but inhibiting two‐atom hydrogenation for overhydrogenation.