Metal–support interactions play a critical role in the catalytic activity of supported organotransition metal catalysts, however, systematic evaluation of these interactions across a wide range of supports remains under investigated. We have developed a method to evaluate these interactions using chemisorbed [Cp*Ir(III)] complexes on metal oxide supports as catalysts for H/D exchange. H/D exchange activity correlates to the covalency of the supported iridium species; reactivity is significantly attenuated for supported catalysts with a higher degree of covalency in the metal–support interaction, such as silica or unfunctionalized zirconia; in contrast, reactivity is enhanced for surfaces that engender ionic character to the metal–oxygen bond, such as in the case of superacific sulfated zirconia or sulfated alumina.<br/><br/>A [Cp*Ir(III)] complex is chemisorbed onto a series of Brønsted acidic metal oxide supports, ranging from silica to superacidic sulfated zirconia. The synthesis and characterization of these catalysts is described, and the surface chemistry is explored by in-situ DRIFTS analysis. Catalytic H-D exchange is evaluated as a probe reaction to assess the activity of each catalyst as a function of surface acidity. The highly electrophilic iridium on sulfated zirconia catalyst promotes hydrogen-deuterium of methane at room temperature, as well as a variety of other organic substrates. This reactivity is significantly attenuated on surfaces with a higher degree of covalency, such as silica or unfunctionalized zirconia.

Catalytic H/D exchange with supported Ir(III) complexes as a probe reaction for metal–support interactions

255th National Meeting (2018)

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