Regioselective Hydrosilylation Catalysis with Supported Well-Defined Pt(0) Complexes: Effects of Surface Anions and
Damien B Culver1, Conor Neill1, Frédéric A Perras1,2
1Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, Iowa 50011, United States.
Abstract:
Achieving stable, selective single-atom catalysts is challenging because localsurface-site structures are difficult to control. Surface organometallic chemistry and organic-inorganic hybrid materials offer partial solutions, but applications to supporting zero-valent metals are limited. We demonstrate that well-defined, ionically bound N-heterocyclic phosphenium ([NHP]+) ligands can be generated on silylium-functionalized sulfated zirconia ([iPr3Si][SZO]). These surface-bound [NHP][SZO] ligands coordinate Pt(0) centers, forming [(NHP)Pt(0)L][SZO] precatalysts that are highly active for alkyne hydrosilylation. Systematic studies reveal that sterically bulky aromatic ligands enhance regioselectivity, achieving performances comparable to molecular Pt catalysts. Further, more-coordinating anions support more-regioselective precatalysts; therefore, SZO supports more-selective species than weaker-coordinating Al(OC(CF3)3)3-functionalized silica, a trend confirmed by molecular analogues. These results demonstrate that both the ligand and support control catalytic behavior and enable solid-state structure-activity relationships.
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