Tandem deoxygenative hydrosilation of carbon dioxide with a cationic scandium hydridoborate and B(CF).

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