Silicon chemistry in zero to three dimensions: from dichlorosilylene to silafullerane

Abstract

Silylenes and silanides, prominent Si(II) species, are not only interesting in their own right, but also constitute important building blocks in oligosilane and organosilane chemistry. The past decade has witnessed tremendous advances in the understanding of the ambiphilic behavior of silylenes and the nucleophilic properties of silanides, as well as the mutual relationships between both species. Especially the readily available SiCl₂/[SiCl₃]⁻ system is intriguing, because it features highly functionalized silicon centers, amenable to late-stage modifications. Moreover, SiCl₂ and [SiCl₃]⁻ are interconvertible by mere chloride association/dissociation. This Feature Article first provides a brief introduction to isolable (functionalized) silylenes and silanides and then focusses on the SiCl₂/[SiCl₃]⁻ couple. Classical high-temperature protocols for the generation of SiCl₂ are juxtaposed with convenient recent solution phase methods that provide access to R₃N–SiCl₂ and [SiCl₃]⁻via deprotonation of HSiCl₃ or the amine-/chloride-induced disproportionation of Si₂Cl₆. We give a comprehensive overview of key mechanistic issues and highlight the utility of R₃N–SiCl₂ and [SiCl₃]⁻ for the synthesis of open-chain and cyclic oligosilanes as well as nanoscale, fullerene-type silicon clusters.