Hexa-, hepta-, and octacyclic ladder polysilanes (5–7) were synthesized, and their structures were determined by X-ray crystallography. These compounds have the double helix structure consisting of two linear polysilane chains. In the UV–visible spectra, the lowest energy absorption maxima of 5–7 shift bathochromically as the number of cyclotetrasilane rings progressively increases.
Synthesis, structures, and oxidation of the ladder oligosilanes, such as bicyclo[2.2.0]hexasilane, tricyclo-[4.2.0.02,5]octasilane, tetracyclo[4.4.0.02,5.07,10]decasilane, and pentacyclo[6.4.0.02,7.03,6.09,12]dodecasilane, are reported.
The radical anions of ladder oligosilanes were generated by the reduction with alkali metals and observed by UV–visible–NIR and ESR spectroscopies. The radical anions of the longer ladder oligosilanes are highly stable at room temperature.