Addition of methyllithium to disilyne RSi&z.tbd;SiR (R = SiiPr[CH(SiMe3)2]), giving a disilenyllithium, and its unexpected isomerization to a disilacyclopropylsilyllithiumCCDC reference number 761497. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c0nj00027bThis article is part of a themed issue on Main group chemistry

The reaction of the isolable disilyne 1 , RSi&z.tbd;SiR (R = Si i Pr[CH(SiMe 3 ) 2 ]), with MeLi produced the methyl-substituted disilenyllithium 2 as the primary product. However, 2 is not thermally stable at room temperature in THF, and slowly isomerized to the unexpected disilacyclopropylsilyllithium, which was characterized by NMR spectroscopy as well as by X-ray crystallography. The reaction of disilyne RSi&z.tbd;SiR (R = Si i Pr[CH(SiMe 3 ) 2 ]) 1 with MeLi produced the methyl-substituted disilenyllithium 2 as the primary product, however, it unexpectedly underwent isomerization to disilacyclopropylsilyllithium 3 .