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A series of aryl disilenes Tip2Si=Si(Tip)Ar (2a–c) and para-arylene bridged tetrasiladienes, Tip2Si=Si(Tip)–LU–Si(Tip)=SiTip2 (3a–d) are synthesized by the transfer of the Tip2Si=SiTip unit to aryl halides and dihalides by nucleophilic disilenides Tip2Si=SiTipLi (Tip = 2,4,6-iPr3C6H2, Ar = aryl substituent, LU = para-arylene linking unit). The scope of the nucleophilic Si=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-Me3C6H2; Ar = Dur = 2,3,5,6-Me4C6H, X = Br or I). Bridged tetrasiladienes Tip2Si=Si(Tip)–LU–Si(Tip)=SiTip2 with more extended linking units surprisingly exhibit fluorescence at room temperature, albeit weak. DFT calculations suggest that partial charge transfer character of the excited state is a possible explanation. [ABSTRACT FROM AUTHOR]

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, Tip2Si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. We show that the thermal stability of the employed bis(alkyne) co-monomer is translated into this polymer. [ABSTRACT FROM AUTHOR]

Reactions of a disilenide, a disila analogue of vinyl lithiums, with two &#945,β-unsaturated carboxylic acid chlorides yield the first examples of compounds with a bicyclo[1.1.1]pentane scaffold that feature one carbon and one silicon atom at bridgehead positions; the formation of 1,2-disilabicyclo[1.1.1]pentan-4-ones is explained with initial nucleophilic substitution at the carbonyl C-atom by the nucleophilic disilenide and subsequent intramolecular [2+2]-cycloaddition of the Si = Si to the C = C double bond in a highly diastereoselective fashion. [ABSTRACT FROM AUTHOR]