Synthesis, Structure, and Facile Ring Flipping of a Bicyclo[1.1.0]tetrasilane

Hexakis(tert-butyldimethylsilyl)bicyclo[1.1.0]tetrasilane
(3), which is known to isomerize to
the corresponding cyclotetrasilene 4 above 0 °C, was synthesized via an alternative synthetic route
and isolated at low temperatures as air-sensitive yellow crystals.
The short-bond structure of 3 was disclosed
by X-ray analysis and DFT calculations, and facile ring flipping of 3 below 0 °C with the activation parameters
of ΔH‡ = 6.67 ± 0.18
kcal mol−1 and ΔS‡ = −22.7 ± 0.8 cal mol−1 K−1 was observed.