A rigid tridentate anilido bipyridyl ligand has been designed for use in an organoscandium based carbon dioxide hydrosilation catalyst.  Metallation of a 3,5-di-tert-butylphenyl group installed for steric bulk renders the ligand tetradentate; double CO2 insertion leads to the catalyst precursor which can be activated using the borane B(C6F5)3.  A hemilabile carboxylate results and hydrosilation of CO2 occurs to selectively produce the bis-silylacetal R3SiOCH2OSiR3 in 94% isolated yield with a TON of ~ 3400 (conversion of silane).  Mechanistic experiments suggest that the sequestration of free B(C6F5)3 by the hemilabile carboxylate contributes to the selectivity observed and prevents over reduction to methane.

New ligand environments for organoscandium complexes capable of CO2 hydrosilation

248th National Meeting (2014)

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