Imino(silyl)disilenes: application in versatile bond activation, reversible oxidation and thermal isomerization

Two novel disilenes of type ABSiSiAB bearingN-heterocyclic imino (A = NI^tBu) and trialkylsilyl (B = Si^tBu₃1, B = Si^tBu₂Me2) groups are reported. The reduced steric demand in2results in a highly stable, nonetheless flexible system, wherefore (E/Z) isomerization is observed from room temperature up to 90C. The proposed isomerization mechanism proceedsviamonomeric silylenes in line with experimental results. Despite enhanced stability, disilene2retains high reactivity in the activation of small molecules, including H₂. The rare example of a disilene radical cation7is isolated and shows reversible redox behavior. White phosphorous (P₄) selectively reacts with2to give the unique cage-compound8. Selective thermal rearrangement of2at higher temperatures yields the A₂SiSiB₂-type disilene9(A = NI^tBu, B = Si^tBu₂Me), which bears characteristics of a zwitterionic and a dative central Si-Si bond. The proposed mechanism proceedsviaan initial NHI migration followed by silyl migration.