Formation and Polymorphism of Semiconducting KSiH and Strategy for Metallization.

KSiH, crystallizing in the cubic KPtCl structure type (3̅), features unusual hypervalent SiH complexes. Here, the formation of KSiH at high pressures is revisited by in situ synchrotron diffraction experiments, considering KSiH as a precursor. At the investigated pressures, 8 and 13 GPa, KSiH adopts the trigonal (NH)SiF structure type (3̅1) upon formation.