Developing Lattice-Confined Chemistry: Synthesis and Application of Binuclear Reaction Sites

Abstract

The selective functionalization of simple hydrocarbons would provide opportunities to utilize currently wasted hydrocarbon fractions as chemical fuels and chemical feedstocks. We are interested in lattice-confined chemistry which confines reactive species inaccessible in molecular analogs.

To this end, we demonstrate the use of ion metathesis chemistry to provide access to novel binuclear platforms to explore M–M cooperation in catalysis. We have utilized ion metathesis within pre-formed coordination polymers to prepare metastable Pd₂(O₂CR)₄ sites in which the confined Pd–Pd interaction is evidenced by its short bond distance. The demonstration of templated ion metathesis to generate specific metastable coordination sites that are inaccessible in solution phase chemistry represents a new opportunity to interrogate the chemistry of specific polynuclear metal aggregates. Nitrogen-atom transfer (NAT) from a lattice-confined Ru₂ nitride to toluene to generate benzylamine is realized. Analogous chemistry is unavailable at molecule site mimics since the side reactions take place when the reactive center in not confined. In operando analysis of intra- and intermolecular deuterium kinetic isotope effect (KIE) establishes the relative rates of substrate diffusion and interstitial chemistry. We utilize KIEs to directly evaluate the impact of material mesoporosity on substrate diffusion during catalysis. The use of KIEs as a tool enables the interrogation of substrate diffusion rate relative to the reaction rate during chemical reaction.