Isomerisation and Insertion Chemistry of Imidosilanes Enabled by Reversible Si(IV)/Si(II) Redox Shuttling.

Spontaneous redox shuttling at silicon is very rare, primarily reflecting the thermodynamic challenges associated with reduction processes for lighter p-block elements. Here we show that the reactions of boryl-substituted silylene {PhC(BuN)}Si{B(NDippCH)} with an organo-azide proceed through a Si(IV)-Si(II)-Si(IV) series of redox processes involving both oxidative and reductive ligand migration steps. Each of the isomeric compounds related through this reaction manifold is isolable (and can be structurally characterised by X-ray crystallography), with the overall free energy profile being close to thermo-neutral. Broader studies within group 14 imply that this redox shuttling is unique to silicon and that reductive ligand migration also plays a role in O-atom insertion chemistry.