Reduction of a Bicyclo[1.1.0]tetrasil-1(3)-ene with LiAlH₄ Leading to an Isolable Cyclotrisilenide

Abstract

We report the reduction of bicyclo[1.1.0]tetrasil-1(3)-ene 1a, which has a bridgehead inverted SiSi bond, with lithium aluminum hydride (LiAlH 4 ) to provide the first isolable cyclotrisilenide 2. Single-crystal X-ray diffraction analysis revealed that 2 exists as a contact ion pair and the lithium cation was ligated by three THF molecules and the anionic silicon atom. The reaction of 1a with MeLi afforded the corresponding 1-methyl-3lithiobicyclo[1.1.0]tetrasilane 3, which provides methyl-substituted cyclotrisilene 4 after protonation. These results suggest that 2 should be formed via the formal 1,2-addition of LiH to the bridgehead SiSi bond of 1a and the subsequent intramolecular hydride migration accompanied by ring-opening. Cyclotrisilenide 2 readily reacted with Me 3 SiCl and Ph 2 PCl to afford the corresponding silyl and phosphanyl-substituted cyclotrisilenes, respectively.

Direct Formation and Reactivity of a Bromo- and Amido-Substituted Cyclotrisilene

“…Instead, NHC Me4 coordinates to one of the silicon atoms of the slightly polarized SiSi double bond (Scheme ). This situation is reminiscent to the DMAP-coordinated chloro-substituted cyclotrisilene reported by Iwamoto and to the NHC-coordinated Cp*- and Trip-substituted cyclotrisilene reported by Scheschkewitz…”

Synthesis of Genuine Germenyl Lithiums and the First Persistent Germenyl Radicals

“…Such compounds have great synthetic potential, including transformations which incorporate E=E′ and C=E bonds into organic molecules [2c] . Several disilenyl anions (disilenides) (R 2 Si=SiR′−M, M=Li, Na, K) were synthesized, [3c–g,k] and their use as precursors for more extended conjugated systems, [3b, 4] functionalized heavier alkenes, [5] heterocycles [6] and E‐clusters, [7] was explored. In contrast, only one example of a digermenide, [3i] (R 2 Ge=GeR′−M), and several digermenide dianions [8] were isolated.…”