First synthesis of a dihydrido functionalized double-cored oligosilane dendrimer

The reaction of (R2MeSi)2SiHCl (2) [R=SiMe3] with Na–K-alloy yields the double-cored dendritic oligosilane [(R2MeSi)2SiH]2 (4). The structure of 4 was obtained from X-ray diffraction data, which verify a total of 14 silicon atoms and a longest chain of six silicon atoms. The UV–Vis spectra of 4 and the structurally analogous [(R2MeSi)2SiMe]2 (5) exhibit absorption maxima (shoulders) at 269 nm (ε=2.0×104) and 276 nm (ε=2.3×104), respectively, which are the longest so far observed for alkyl substituted oligosilanes with hexasilane chains.