Surface Organomettalic Chemistry of Group III Metal Alkyls

Alexander Stant, Keith Searles

University of Florida

Despite heterogenous catalysts being fundamental to our society for many decades, the active sites for some of these catalysts remain a topic of debate. This is largely because traditional heterogeneous synthetic techniques generally create a non-uniform catalyst exhibiting a variety of surface/active sites, making characterization of catalytically active species extremely challenging, if not impossible. An emerging field known as surface organometallic chemistry (SOMC) has gained interest as an approach that combines the advantages of both of molecular chemistry and heterogeneous catalysis. SOMC takes inorganic oxides, particularly silica (SiO₂) or Alumina (Al₂O₃) and treats them like a ligand that can react with metal precursors via protonolysis to form chemically anchored and characterizable catalysts. While group IV SOMC supported metals have shown precedence for alkane hydrogenolysis, group III remains largely underexplored. This talk highlights bridging the homogeneous reactivity of group III metals with the established techniques and methodologies of the SOMC to design materials for activating hydrocarbon substrates. Sigma bond metathesis is a critical step in activating alkanes and involves the reaction of an alkane with a metal hydride to release molecular hydrogen and generate a newly formed metal alkyl species. This alkyl species is an entry point to subsequent alkane functionalization. SOMC techniques and methodologies will be utilized to generate well-defined scandium and yttrium surface sites for the study of oxide supported rare earth metal alkyls and hydrides. This work aims to create a better understanding of rare earth supported catalysts, which ultimately will lead to structure activity relationships and rational catalyst design for hydrocarbon conversions.