(Oligo)aromatic species with one or two conjugated Si[double bond, length as m-dash]Si bonds: near-IR emission of anthracenyl-bridged tetrasiladiene.

A series of aryl disilenes TipSi[double bond, length as m-dash]Si(Tip)Ar (2a-c) and para-arylene bridged tetrasiladienes, TipSi[double bond, length as m-dash]Si(Tip)-LU-Si(Tip)[double bond, length as m-dash]SiTip (3a-d) are synthesized by the transfer of the TipSi[double bond, length as m-dash]SiTip unit to aryl halides and dihalides by nucleophilic disilenides TipSi[double bond, length as m-dash]SiTipLi (Tip = 2,4,6-iPrCH, Ar = aryl substituent, LU = para-arylene linking unit). The scope of the nucleophilic Si[double bond, length as m-dash]Si transfer reaction is demonstrated to also include substrates of considerable steric bulk such as mesityl or duryl halides Ar-X (Ar = Mes = 2,4,6-MeCH; Ar = Dur = 2,3,5,6-MeCH, X = Br or I). Bridged tetrasiladienes TipSi[double bond, length as m-dash]Si(Tip)-LU-Si(Tip)[double bond, length as m-dash]SiTip with more extended linking units surprisingly exhibit fluorescence at room temperature, albeit weak.

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 σ-π 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, Tip2 Si=SiTip-pC6H4-SiTip=SiTip2 (Tip = 2,4,6-iPr3C6H2). The polymer obtained from the extended monomer and further tetrasiladiene exhibits pronounced σ-π conjugation, as was evident from the red-shift in the absorption spectrum compared to model systems.

Transfer of a disilenyl moiety to aromatic substrates and lateral functional group transformation in aryl disilenes.

The reaction of 1 equiv of the disilenide Tip2Si═Si(Tip)Li (5; Tip = 2,4,6-(i)Pr3C6H2) with para-substituted phenyl iodides, 4-X-PhI, transfers the Tip2Si═Si(Tip) moiety with elimination of lithium iodide to yield the laterally functionalized disilenes Tip2Si═Si(Tip)(4-X-Ph) [X = H (6a), F (6b), Cl (6c), Br (6d), I (6e)]. The UV-vis absorptions of 6a-d suggest a linear correlation with electronic Hammett parameters. In addition, X-ray structural analyses of 6a-d verified the theoretically predicted linear dependence of the Si═Si bond length and trans-bent angles.