Facile Conversion of Bis-Silylene to Cyclic Silylene Isomers: Unexpected C–N and C–H Bond Cleavage

Reaction
of thiolate 1 with carbene-stabilized diiodo-bis-silylene
(2) (in a 2:1 ratio) in THF unexpectedly gives both the
first five-membered, sulfur-containing, zwitterionic silylene ring
(3) via insertion of the “SiI2” unit of 2 into the olefinic CH bond
of the imidazole ring of 1 and four-membered cyclic silylene
(4) via insertion of a silicon­(I) atom of 2 into the CphenylN bond of the carbene ligand.
The parallel reaction in toluene only gives 3 as the
major product. The nature of the bonding in isomeric 3 and 4 was probed by experimental and theoretical methods.

硫醇盐1（thiolate 1）与卡宾稳定化二碘双硅烯（carbene-stabilized diiodo-bis-silylene）2以2:1的摩尔比在四氢呋喃（THF）中反应，意外同时生成两种产物：一是将化合物2中的“SiI₂”单元插入至化合物1的咪唑环的烯烃C—H键中，得到首例含硫五元环两性离子硅烯环（3）；二是将化合物2中的硅(I)原子插入至卡宾配体的苯基碳-氮键中，得到四元环硅烯（4）。在甲苯（toluene）中进行的平行反应仅以3为主要产物。研究人员通过实验与理论方法对异构体3与4中的成键本质展开了探究。