Ternary Hypervalent Silicon Hydrides via Lithium at High Pressure

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.

6 pages, 4 figures