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

摘要

Two novel disilenes of type ABSi=SiAB bearing N-heterocyclic imino (A = (NIBu)-Bu-t) and trialkylsilyl (B = (SiBu3)-Bu-t 1, B = (SiBu2Me)-Bu-t 2) groups are reported. The reduced steric demand in 2 results in a highly stable, nonethe-less flexible system, wherefore (E/Z) isomerization is observed from room temperature up to 90 degrees C. The proposed isomerization mechanism proceeds via monomeric silylenes in line with experimental results. Despite enhanced stability, disilene 2 retains high reactivity in the activation of small molecules, including H-2. The rare example of a disilene radical cation 7 is isolated and shows reversible redox behavior. White phosphorous (P-4) selectively reacts with 2 to give the unique cage-compound 8. Selective thermal rearrangement of 2 at higher temperatures yields the A(2)Si=SiB2-type disilene 9 (A = (NiBu)-Bu-t, B = (SiBu2Me)-Bu-t), which bears characteristics of a zwitterionic and a dative central Si-Si bond. The proposed mechanism proceeds via an initial NHI migration followed by silyl migration.