Ternary hypervalent silicon hydrides via lithium at high pressure

Hydrogen is rarely observed as a ligand in hypervalent species, however, we find that high-pressure hydrogenation may stabilize hypervalent hydrogen-rich materials. Focusing 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 different hypervalent anions: layered SiH₅^- and tricapped triangular prismatic SiH₆^{2 -} . These differ from octahedral SiH₆^{2 -} described in earlier studies. In addition, there are further hydrogen-rich structures, Li₃SiH₁₀ and Li₂SiH_{6 +δ} , which may be stabilized at high pressure. Our work provides pointers to future investigations on hydrogen-rich materials.