Tandem deoxygenative hydrosilation of carbon dioxide with a cationic scandium hydridoborate and B(C6F5)(3)

摘要

A scandium hydridoborate complex supported by the dianionic pentadentate ligand B(2)Pz(4)Py is prepared via hydride abstraction from the previously reported scandium hydride complex with tris-pentafluorophenyl borane. Exposure of [(B(2)Pz(4)Py)Sc][HB(C6F5)(3)] to CO2 immediately forms [(B(2)Pz(4)Py)Sc][HCOOB(C6F5)(3)] at room temperature. The formatoborate complex can also be synthesized directly from the starting material (B(2)Pz(4)Py)ScCl with Et3SiH and B(C6F5)(3) while in the presence of an atmosphere of CO2 in 81% yield. This compound was evaluated as the transition metal component of a tandem deoxgenative CO2 hydrosilation catalyst. At 5% loadings, complete consumption of Et3SiH was observed along with CO2 reduction products, but conversion to an inactive scandium complex identified as (B(2)Pz(4)Py)ScOSiEt3 was observed.