Siladodecahedranes: studies on reactivity, bonding situation, and optoelectronic properties.

• Applicant: Professor Dr. Matthias Wagner
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 506550642

We will investigate in detail the experimentally largely unexplored substance class of siladodecahedranes. While numerous theoretical papers document a keen interest in this topic, it was only in 2015 that the anion [Cl@Si32Cl44]‒, the first preparatively accessible siladodecahedrane, was described by our group (27% yield over only one reaction step). Recently, we also published the perhydrogenated ([Cl@Si20H20]‒) and perchlorinated ([Cl@Si20Cl20]‒) siladodecahedranes. For compound analysis, we have optimized mass spectrometric methods and recognized the rarely used 35/37Cl NMR spectroscopy as a powerful tool. Basically, clusters can be modified in three ways: i) surface modification, ii) cluster expansion/contraction by insertion/extrusion reactions, and iii) cluster opening by scaffold-bond cleavage. Since our clusters are a completely new class of materials to be comprehensively investigated, we aim to cover all three areas in this project, with flexibility to adjust the individual weights depending on the results during the course of the project. From this, we derive the following work packages (WP):- WP1: Derivatization of the Si32 framework, starting from [Cl@Si32Cl44]‒, [Cl@Si32H44]‒ and [Cl@Si32H36Me8]‒, in particular by nucleophilic/electrophilic exchange and hydrosilylation reactions.- WP2: Derivatization of the Si20 framework starting from [Cl@Si20Cl20]‒ and [Cl@Si20H20]‒, in particular by nucleophilic/electrophilic exchange and substituent abstractions.- WP3: Investigation of the electronic structure of the (Si)n clusters by NMR spectroscopy, UV-vis and emission spectroscopy on suitable push-pull derivatives, cyclic voltammetry and quantum chemical calculations (cooperation with AK Grimme).- WP4: Modification of the Si20 cluster by insertion of atoms (e.g. O) or reactive molecules (e.g. :CR2) into individual polyhedral edges (cage extension). Cage opening by reductive (e.g. [Cl@Si20H20]‒ using alkali metals) or oxidative (e.g. [[Cl@Si20Cl20]‒ using Cl2) cleavage of individual Si-Si bonds of the cage.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Hans-Wolfram Lerner