Identification of branched oligosilanes in the phenylsilane dehydrocoupling reaction

The products of phenylsilane dehydrocoupling were analyzed by means of advanced NMR techniques including LC–NMR. Attention was paid to the –SiPh– units not containing Si–H bonds. These units were observed in the 29Si NMR spectra reported previously. The 1J and 2J29Si INADEQUATE experiments were used to reveal the connectivities within oligosilane chains. The presence of the branched oligophenylsilanes was confirmed in the reaction catalyzed by Cp2Ti(OAr)2, Ar = (2,6-(iPr)2C6H3). Furthermore, the formation of silyl-substituted cyclic oligomers and the presence of branched oligophenylsilanes in the catalytic systems studied by other authors were discussed. The LC–NMR and INADEQUATE experiments were optimized using the linear and low oligomeric products which were obtained by other catalysts. Some of these results are also presented.

The presence of the branched oligophenylsilanes in the metallocene catalyzed dehydrocoupling polymerization of phenylsilane is demonstrated on the reaction catalyzed by Cp2Ti(OAr)2, Ar = (2,6-(iPr)2C6H3).Figure optionsDownload as PowerPoint slideHighlights
► The presence of branched silanes in dehydrocoupling reaction is shown.
► The signal of the branched tetramer and pentamer was assigned in 29Si NMR spectrum.
► The typical region (∼−56 ppm) of the terminating unit PhSiH2–SiPh< was identified.