SYNTHESIS AND MOLECULAR-STRUCTURE OF SILYLATED ETHENES AND ACETYLENES

Disilylacetylene (1) has been obtained from LiAlH4 reduction of bis(tr ichlorosilyl)acetylene (2) and bis[(trifluoromethylsulfonyloxy)silyl] acetylene (4). The catalytic hydrosilylation of 2 with HSiCl3 affords tris(trichlorosilyl)ethene (5) and 1,1,2-tris(trichlorosilyl)ethane (6 ). The synthesis of 6, trans-bis(trichlorosilyl)ethene (8) and 1,1-bis (trichlorosilyl)ethene (9) has been accomplished by hydrosilylation of trichlorosilylacetylene (7) which was synthesized by the reaction of trichloro(trifluoromethylsulfonyloxy) silane with sodium acetylide. Re ductive elimination of halogen from 1,1,1, 2-tetrachloro-bis(trichloro silyl) ethane (10) and 1,2-dibromo-1,1-bis(trichlorosilyl)ethane (13) gave the corresponding ethenes 1,1-dichloro-bis(trichlorosilyl)ethene (11), trichloro-trichlorosilylethene (12), 1,1-bis(trichlorosilyl) eth ene (9) and 1-chloro-2,2-bis(trichlorosilyl)ethene (14). Tetrakis(tric hlorosilyl)ethene (15) has been obtained in a three step synthesis sta rting from chloromethyl-trichlorosilane or dichloro-methyl-trichlorosi lane. By LiAlH4 reduction of trichlorosilylethenes under various react ion conditions, the silylethenes trans-dichloro-di(silyl)ethene (16), 1,1-dichloro-di(silyl)ethene (17), trichloro-silylethene (18), 1-bromo -1-silylethene (19), trans-di(silyl)ethene (20), 1-chloro-2,2-di(silyl ) ethene (21), tri(silyl)ethene (22) and 1,1,2-tri(silyl)ethane (23) c ould be generated. Silylethyne and silyl-chloroethyne were identified as side products The crystal and molecular structures of 2, 5 and 15 h ave been determined by single crystal X-ray diffraction. 2 and 5 cryst allize from the melt in the monoclinic space groups Cc and P2(1)/n, re spectively. 15 has been crystallized by sublimation (orthorhombic, spa ce group Pbca). 5 and 15 feature strongly distorted ethene skeletons w ith a double bond twist of 28.1 degrees in 15.