Three-membered cyclic digermylenes stabilised by an N-heterocyclic carbene

Treatment of potassium salts of silole dianions with donor stabilised germanium dichlorides gave the anticipated silagermafulvenylidenes R2Si = Ge(Do) (R2Si = 1-silacyclopentadiendiyl, Do = N-heterocyclic carbene (NHC)) only as transient intermediates in a side reaction. They were detected by NMR spectroscopy and, in one case, the formal dimer, 2,4-disila-1 lambda(3),3 lambda(3)-digermetane, was isolated. The main products of these reactions are sila-bis-lambda(3)-germiranes, i.e. directly interconnected digermylenes that are part of a three-membered ring. The structural data, supported by the results of density functional calculations confirm the digermylene nature of these products with a long inner cyclic Ge-Ge bond that decreases the inherent high ring strain in silagermiranes.

Automated summary

The treatment of potassium salts of silole dianions with donor stabilised germanium dichlorides resulted in the formation of anticipated silagermafulvenylidenes as transient intermediates, rather than the desired products. The main products of these reactions are sila-bis-lambda(3)-germiranes, directly interconnected digermylenes that are part of a three-membered ring. The structural data, supported by density functional calculations, confirm the digermylene nature of these products with a long inner cyclic Ge-Ge bond that decreases the high ring strain in silagermiranes.