SYNTHESIS, SPECTROSCOPY AND STRUCTURE OF PHENYLATED CYCLOPENTASILANES

Phenylated cyclopentasilanes Si(5)Ph(10-n)X(n) with X = OSO2CF3, F, Cl , Br, I or H and n = 1 or 2 were prepared in high yield by dearylation of Si(5)Ph(10) with trifluoromethanesulphonic acid (CF3SO3H) and subs equent reaction with lithium or potassium halides and LiAIH(4). The tr ans-1,3-isomers of Si(5)Ph(8)X(2) were isolated by crystallization and the crystal structure of trans-1,3-difluorooctaphenyl-cyclopentasilan e was determined. cis-1,3-, trans-1,2- and cis-1,2-Si(5)Ph(8)X(2) were identified and characterized by H-1, F-19 and Si-29 NMR spectroscopy. Si-Si coupling constants were measured using INADEQUATE pulse sequenc es.