Dichlorogermylene-dioxane complex reactions

The mechanism of the formation of a three-membered unsaturated ring was clarified later, when this reaction was reexamined by the same authors in detail . They found that the reaction of dichlorogermylene-dioxane complex with one equivalent of f-BusSiNa in THF at —78 °C led to the formation of c ,frawi-l,2,3-trichloro-l,2,3-tris(tri-terf-butylsilyl)cyclotrigermene 7 in 98% yield (Scheme 4). The cis,trails conformation of 7 was established by NMR spectroscopy and X-ray analysis (Figure 3). Treatment of 7 with two equivalents of f-Bu3SiNa in TFIF at —78°C cleanly produced cyclotrigermene 5 (Scheme 4), which gives evidence that 7 is a precursor for 5. 

The insertion reaction can be easily modeled by using the dioxane complex of dichlorogermylene24,49. Kinetic investigation of the reaction with benzyl chloride was carried out50. The experimental data were in line with kinetic equation 9, which involves participation of a free dichlorogermylene in the insertion step (in dioxane solution, where the equilibrium is shifted to the left, the insertion reaction does not occur). 

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