PREPARATION OF A DIETHYNYL HYPERVALENT SILICON MONOMER BY COORDINATION-SELECTIVE CLEAVAGE - STRUCTURE AND POLYMERIZATION TO GIVE NOVEL POLYCARBOSILANES CONTAINING MAIN-CHAIN HEXACOORDINATE SILICON

The hexacoordinate monomer R(2)Si(C=CH)(2) [R = 8-(dimethylamino)napht hyl; the X-ray crystal structure showing both nitrogens trans to the e thynyl groups], formed from R(2)Si(C=CSiMe(3))(2) by coordination-sele ctive cleavage of the trimethylsilyl-acetylene bonds in the presence o f Bu(4)(n)NF, undergoes palladium-catalysed cross-coupling polymerizat ion with dihaloarenes to afford novel polycarbosilanes [R(2)SiC=CArC=C ](n) (Ar = 1,4-phenylene, 4,4'-biphenylene, 9,10-anthrylene) containin g hexacoordinate silicon.