Ternary Hypervalent Silicon Hydrides via Lithium at High Pressure

TL;DR

This study explores how high-pressure hydrogenation stabilizes hypervalent silicon hydrides with lithium doping, revealing new anions and structures that could inform future hydrogen-rich material research.

Contribution

The paper reports the discovery of new hypervalent silicon hydride anions and structures stabilized under high pressure, expanding understanding of hydrogen-rich silicon compounds.

Findings

Identification of layered-SiH₅⁻ and SiH₆²⁻ anions.

Discovery of hydrogen-rich structures Li₃SiH₁₀ and Li₂SiH₆+δ.

High-pressure stabilization of novel silicon hydrides.

Abstract

Hydrogen is rarely observed as ligand in hypervalent species, however, we find that high-pressure hydrogenation may stabilise hypervalent hydrogen-rich materials. Focussing on ternary silicon hydrides via lithium doping, we find anions composed of hypervalent silicon with H ligands formed under high pressure. Our results reveal two new hypervalent anions: layered-SiH$_{5}^{-}$ and tricapped trigonal prismatic SiH$_{6}^{2-}$. These differ from octahedral SiH$_{6}^{2-}$ described in earlier studies. In addition, there are further hydrogen-rich structures Li$_{3}$SiH$_{10}$ and Li$_{2}$SiH$_{6+\delta}$ which may be stabilised at high pressure. Our work provides pointers to future investigations on hydrogen-rich materials.