Synergistic Behavior of Bimetallic Rhenium Cluster Catalysts: Spectroscopic Investigation into the Nature of the Active Site

Single‐site Re nanoparticles were produced by anchoring dirhenium organometallic clusters on to the inner walls of mesoporous silica. The presence of oxophilic atoms (Sb or Bi) is essential to obtain well dispersed Re0 centers. The interaction between the organometallic cluster and the silica support is critical for the generation of well‐defined and isolated Re0 single sites. FTIR spectroscopy was used to track the decomposition of the organometallic precursors and the adsorption of probe molecules such as CO on the metal sites sheds valuable information on the catalytic potential of this new class of bimetallic nanocatalysts. Single sites: The interaction between the organometallic cluster complexes (see figure) and the silica support is the driving force that leads to the generation of Re0 single sites, which are active for the ammoxidation of 3‐picoline to nicotinonitrile (which is a precursor for vitamin B3). The key step in the decomposition of the dirhenium precursor complexes is the loss of the phenyl groups from the oxophile and its subsequent binding to the silica surface.