Single-site, molecule derived supported catalysts have attracted interest due to their hybrid character combining the complementary features of traditional hetero- and homogeneous systems. In particular, electrophilic d0 catalysts supported on “super” Brønsted acids exhibit large percentages of catalytically significant sites (70-90%) with high activity for technologically relevant olefin polymerization and hydrogenation processes. Catalysts of the type Cp*ZrR2/ZrS (Cp* = Me5C5, R = methyl or benzyl, ZrS = sulfated zirconia) demonstrate novel selectivity patterns for arene hydrogenation. In the instance R = methyl, benzene selective hydrogenation, a potential approach for carcinogenic benzene removal from gasoline, is achieved with 80% selectivity. Structural and computational studies by solid-state NMR spectroscopy, XAS, and periodic DFT argue that the “cationic” metal center-anionic surface distance affects the competitive inhibition, and thus the selectivity, for this catalyst. For the catalyst with R = benzyl, the single-face/all-cis hydrogenation of a large series of alkylated and fused arene derivatives to the corresponding all-cis-cyclohexanes. Kinetic/mechanistic and DFT analysis argue that stereoselection involves rapid, sequential H2 delivery to a single catalyst-bound arene face, versus any competing intramolecular arene pi-face interchange.

Supported single-site d0 organozirconium complexes for (stereo) selective catalysis

253rd National Meeting (2017)

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