High-temperature- and high-pressure-induced formation of the Laves-phase compoundXeS2

We explore the reactivity of xenon with sulfur under high pressure, using unbiased structure searching techniques combined with first-principles calculations, which identify a stable ${\mathrm{XeS}}₂$ compound crystallized in a Laves phase with hypercoordinated (16-fold) Xe at 191 GPa and 0 K. Taking the thermal effects into account, we find that increasing the temperature could further stabilize it. The formation of ${\mathrm{XeS}}₂$ is a consequence of pressure-induced charge transfer from Xe to S atoms and the delocalization of Xe $5p$ and S $3p$ electrons. Meanwhile, the stabilization into a Laves phase of ${\mathrm{XeS}}₂$ is the result of delocalized chemical bonding and the need for optimum structure packing. The present discussion of the formation mechanism in ${\mathrm{XeS}}₂$ is general, and conclusions can be used to understand the formation of other Laves-phase compounds and the Xe chemistry that allows closed-shell Xe to participate in chemical reactions.