SYNTHESIS AND STRUCTURE OF POLYSILACYCLIC ALKYNES AND ALLENES

Six membered cyclic polysilaacetylenes were prepared by direct reactio n of 1,4-dichlorotetrasilane with acetylene di-Grignard reagents. The reaction of cyclic polysilaacetylenes was studied. Similarly, several different types of cyclic polysilaallenes were prepared by direct reac tion of dihalopolysilanes with either allene dianions and tetraanions. The longer bond length of Si-Si than that of C-C bond makes possible to synthesize highly strained unsaturated cyclic compounds, which had been unable to isolate. Herein, synthesis and structure of polysilacyc lic alkynes, allenes, bisallenes, and betweenallene are discussed.