Polysilane Dendrimers

摘要

Dendrimers with a regular, three-dimensional, tree-like structure have attracted much attention as well-defined macro-molecules. Polysilane dendrimers containing Si atoms connected to three or four other Si atoms should be quite interesting in relation to linear one-dimensional polysilanes. Despite several attempts at the synthesis of polysilane dendrimers, the molecular weight distribution and uniformity of branching could not be strictly controlled. We wish to report the structurally defined synthesis of polysilane dendrimers up to the second generation with a molecular weight of 1832.9. 2-Lithio-1,3-diphenylpentamethyltrisilane, PhMe_2SiMeSi(Li)-SiMe_2Ph (1a), was used as a key intermediate for the synthesis of polysilane dendrimers. The lithium reagent la was prepared and isolated as highly inflammable yellow crystals by the reaction of bis(1,3-diphenylpentamethyltrisilanyl)mercury and lithium in 80% yield (Scheme 1).