Synthesis of polysilanes bearing pendant carbosilyl groups and 29Si-NMR probe on the tacticity using side chain silicon atoms

New functional polysilanes [(R2RSi)-Si-1(CH2)(2)SiH](0) (R = Me. R-1 =H (1) R =R-1 =Et (2): R = Me. R-1 = Ph (3)) bearing carbosilyl side chains have been synthesized by catalytic dehydropolymerization of precursor carbosilanes (R2RSiCH2CH2SiH3)-Si-1 using Cp2TiCl2-BuLi as a catalyst. These polymers are characterized by H-1, C-13, Si-29, {H-1-Si-29} HSQC NMR spectroscopy, GPC and TGA. Attempts to delineate the tacticity from the analysis of deconvoluted Si-29{H-1}-NMR signals associated with the side chain silicon atoms reveal that the triad concentration ratio follows a Bernoullian statistical model for polymers I and 2 only. (C) 2002 Elsevier Science B.V. All rights reserved.