σ-π Conjugated Organosilicon Hybrid Polymers from Copolymerization of a Tetrasiladiene and 1,4-Diethynylbenzene

A catalyst- and by-product-free protocol for the synthesis of sigma-pi conjugated organosilicon polymers is reported. The regiospecific [2+2] cycloaddition of C C triple bonds to Si=Si double bonds allowed the preparation of air-stable ethynyl-terminated extended monomers from 1,4-bis( ethynyl) benzene and the para-phenylene bridged tetrasiladiene, Tip(2)Si=SiTip-pC(6)H(4)-SiTip=SiTip(2) (Tip=2,4,6=iPr(3)C(6)H(2)). The polymer obtained from the extended monomer and further tetrasiladiene exhibits pronounced sigma-pi conjugation, as was evident from the red-shift in the absorption spectrum compared to model systems. We show that the thermal stability of the employed bis(alkyne) co-monomer is translated into this polymer.