The reactions of bridged tris(trimethylsilyl)silyl fragments with 2 molar equiv of potassium tert-butoxide allow the generation of R,ω-oligosilyl dianions (1a, 2a, 3a, 4a). Depending on the nature of the spacer between the oligosilyl units, these compounds can be used to generate either linear or cyclic derivatives. They are especially attractive for the formation of homoand heterocyclosilanes, as exemplified by the synthesis of sila-, stanna-, and zirconocenacyclosilanes. A linear bis(potassiumsilyl)acetylene (4a) was used to bridge two zirconocene units, (Cp 2 Zr(Cl)Si(SiMe 3 ) 2 CCSi(SiMe 3 ) 2 Zr(Cl)Cp 2 ) (11).

Multiply metalated oligosilanes: Treatment of bridged bis[tris(trimethylsilyl)silyl] compounds with two equivalents of potassium tert‐butoxide leads to the formation of 1,3‐ and 1,4‐dipotassium silanes [Eq. (1)]. Reaction of the latter with zirconocene dichloride and hafnocene dichloride, respectively, gives the corresponding metallacyclopentasilanes.

A number of differently substituted oligosilyl potassium compounds have been prepared by reaction of the respective trimethylsilylated precursors with potassium tert-butoxide. It has been demonstrated that in the presence of larger trialkylsilyl groups always trimethylsilyl groups are removed selectively. This selectivity enables the syntheses of oligosilylanions with different sterical demand. By transmetalation of the oligosilyl potassium compounds with halides of less electropositive metals also the reactivity of the silyl anions can be controlled.

In this work the authors report monolithic organic tandem solar cells. The front cell is fabricated from a blend of poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C61-butyric acid methyl ester while a copper phthalocyanine/fullerene (CuPc∕C60) bilayer is used for the back cell. An intermediate recombination zone is realized using two doped organic semiconductor layers and a thin noble metal interlayer. The active polymer layer thickness is optimized to ensure matching of the subcell currents. The open circuit voltage Voc=1V nearly reaches the sum of the open circuit voltages of each contributing cell.

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