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The polysilanes [RMe2Si(CH2)x(Me)Si]n [x = 2, 3; R = 2‐Fu (1, 2), 5‐Me‐2‐Fu (3, 4)] bearing furyl‐substituted carbosilyl side chains have been synthesized by dehalocondensation reaction (Wurtz coupling) of the corresponding carbosilanes using sodium dispersion in refluxing toluene. On the other hand, analogous polysilanes with appended thienyl groups [x = 2, 3; R = 2‐Th (5, 6), 4‐Me‐2‐Th (7, 8)] are only accessible by the reaction of the corresponding carbosilane precursors under mild Wurtz coupling conditions (THF, RT). These polysilanes reveal monomodal molecular weight distribution with Mw/PDI = 3.3–5.4 × 104/1.22–1.47 (1–4) and 9.1–14.4 × 104/1.45–1.61 (5–8) and are characterized by FT‐IR, multinuclear (1H, 13C{1H}, 29Si{1H}) NMR, and UV/PL spectral studies as well as thermogravimetric analysis (TGA). Preliminary studies on the reactivity of polysilane 2 with palladium acetate (toluene, RT) reveal the formation of spherical palladium nanoparticles of size 8.2 ± 0.6 nm, which remain stable in solution for several weeks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7816–7826, 2008

Several new poly(alkylarylsilane)s, [Et 3 Si(CH 2 ) 2 Si(C 6 H 4 R)] n [R = H (1), p-Me (2), p-OMe (3), p-NMe 2 (4)] with M w = 2.9-4.6 Â 10 3 and PDI = 1.41-1.64, have been synthesized by dehalocondensation of appropriate dichlorodiorganosilanes using Na dispersion in refluxing toluene. The σ-σ* electronic transitions associated with the silicon backbone of 1-4 exhibit a progressive red shift (λ max : 320-342 nm) as a result of increasing electron donating ability of the substituent on the phenyl ring. This intrinsic optimization of band gap energy has been considered as a measure of oxidation potential of these polysilanes which varies in the following order: 1 > 2 > 3 > 4. The result obtained from electronic spectra is further confirmed by electrochemical studies using cyclic voltammetry which reveals a lowering of the oxidation potential (V peak ) from 0.95 to 0.49 V in the polysilanes 1-4. These polysilanes act as reducing agents of variable strengths toward Ag(I) and Pd(II) ions and afford the formation of metal nanoparticles with optimized size domains [21.0-4.8 nm for Ag; 31.6-16.6 nm for Pd], the smaller size nanoparticles being formed by the use of polysilanes with lower oxidation potential (or higher λ max ). The polymer-metal nanocomposites have been characterized by NMR and UV-vis spectroscopy as well as powder X-ray diffraction, TEM, and DLS studies.

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The scope of Wurtz coupling and catalytic dehydrocoupling methods for the synthesis of functional polysilanes of compositions, [RR'Si] n (linear), [(PhMeSi) x-co-(RSi) 1−x ] n (branched) and [RSi] n (network) [R = Et 3 SiCH 2 CH 2 , 2-Fu/2-ThMe 2 SiCH 2 CH 2 (Fu = Furyl, Th = Thienyl), n-Hex or Ph; R' = H or Me] is presented. By virtue of σ-delocalized silicon backbone and variable HOMO-LUMO band gap energies, these polymers are found to be promising candidates as reducing agents for Ag(I) ions in toluene/cyclo-hexane and provide a simple approach for 'size-controlled' synthesis of silver nanoparticles (AgNPs) as well as fluorescent polymer-silver nanocomposites.