Synthesis and decomposition of bis(alkoxyethynyl)dimethyltin

The reaction of bis(diethylamino)dimethyltin, Me2Sn(NEt2)2 with methoxy (a) and ethoxyethyne (b) at 0°C affords the bis(alkoxyethynyl)dimethyltin derivatives Me2Sn(CCOR)2 (5a, b) without side products in high yield. Both 5a and 5b decompose slowly at room temperature or much faster at 60–70°C almost quantitatively into an unidentified polymer, small amounts of numerous unidentified methyltin compounds, and mainly 1,1-bis(alkoxy)-2,2-bis[(alkoxyethynyl)dimethyl-stannyl]ethene. The new compounds were characterised by 1H-, 13C- and 119Sn-NMR spectroscopy.