Low-Coordinate Barium Boryloxides: Synthesis and Dehydrocoupling Catalysis for the Production of Borasiloxanes.

The first soluble barium boryloxides [Ba]- OB{CH(SiMe3 )2 } are presented. These mono- or dinuclear complexes feature low coordination numbers, as low as two for [Ba(OB{CH(SiMe3 )2 }2 )2 ], which is further stabilized by intra- and intermolecular Ba⋅⋅⋅H3 C agostic interactions. Barium boryloxides and the parent [Ba{N(SiMe3 )2 }2 ⋅(thf)2 ] catalyze the dehydrocoupling of borinic acids with hydrosilanes, providing borasiloxanes under mild conditions.