Tandem Deoxygenative Hydrosilation of Carbon Dioxide with a Cationic Scandium Hydridoborate and B(C6F5)3

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(C 6 F 5 ) 3 ] to CO 2 immediately forms [(B 2 Pz 4 Py)Sc][HCOOB(C 6 F 5 ) 3 ] at room temperature. The formatoborate complex can also be synthesized directly from the starting material (B 2 Pz 4 Py)ScCl with Et 3 SiH and B(C 6 F 5 ) 3 while in the presence of an atmosphere of CO 2 in 81% yield. This compound was evaluated as the transition metal component of a tandem deoxgenative CO 2 hydrosilation catalyst. At 5% loadings, complete consumption of Et 3 SiH was observed along with CO 2 reduction products, but conversion to an inactive scandium complex identified as (B 2 Pz 4 Py)ScOSiEt 3 was observed