An Efficient Multi-Gram Access in a Two-step Synthesis to Soluble Nine-atomic Silylated Silicon Clusters

Abstract Silicon is by far the most important semiconducting material. However, solution-based synthetic approaches for unsaturated silicon-rich molecules require less efficient multi-step syntheses. We report on a straightforward access to soluble, polyhedral Si9 clusters from the binary phase K12Si17, which contains both [Si4]4- and [Si9]4- clusters. [Si4]4- ions, characterised by a high charge per atom ratio, behave as strong reducing agents, preventing [Si9]4- from directed reactions. By the here reported separation of [Si4]4-, Si9 clusters are isolated as monoprotonated [Si9H]3- ions on a multi-gram scale and further crystallised as their 2.2.2 Cryptate salt. 20 grams of the product can be obtained through this two-step procedure - a new starting point for silicon Zintl chemistry such as the first isolation and structural characterisation of a trisilylated [MeHyp3Si9]- cluster.