The Higher Propensity of Pd-SiHEt₂⁺ over Pd-SiMe₂Et⁺ to Transfer Silylium to Silyl Ether Intermediates Explains Divergent Products in Ketone Hydrosilylation Catalysis

The catalytic use of silylpalladium cations has been developed for the hydrosilylation of ketones. Product outcome was heavily influenced by hydrosilane identity with tertiary silanes providing silyl ethers and secondary silanes, alkanes. Stoichiometric studies suggest a key differentiating feature is the ability to transfer silylium from XantPhosPd-SiR3+ to silyl ether intermediates in the case of secondary silanes but not tertiary. Formation of a bimetallic Pd species during catalysis with secondary silanes points to silylpalladium cations behaving as a source of both electrophilic silylium ions and nucleophilic Pd(0).