Ultrasound-mediated reductive condensation synthesis of silicon- silicon bonded network polymers.

The synthesis of the first polyalkylsilynes [RSi] sub n, a previously unknown class of silicon-silicon bonded network materials, has been accomplished using high-intensity ultrasound to promote the homogeneous reduction of alkylsilicon trichlorides with liquid NaK alloy. This procedure provides good control of reaction kinetics and stoichiometry by ensuring instantaneous, NaK-addition controlled reaction rates at near ambient temperatures. The new polymers, [RSi] sub n (R = n-propyl, n-butyl, n-hexyl), remain soluble in organic solvents, from which they can be cast into transparent yellow films. Chemical and spectroscopic data indicate that the polysiylnes are constructed primarily of sp sup 3 -hybridized alkylsilicon units assembled via Si- Si bonds into irregular networks. Thus these polysilynes provide unprecedented examples of soluble materials possessing a sigma- bonded structure intermediate between that of linear polysilanes and elemental silicon.