K2SiF6 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to six equivalent F(1) and six equivalent F(2) atoms to form distorted KF12 cuboctahedra that share corners with six equivalent K(1)F12 cuboctahedra, corners with three equivalent Si(1)F6 octahedra, faces with two equivalent K(1)F12 cuboctahedra, faces with six equivalent K(2)F12 cuboctahedra, and faces with three equivalent Si(1)F6 octahedra. The corner-sharing octahedral tilt angles are 15°. In the second K site, K(2) is bonded to six equivalent F(1) and six equivalent F(2) atoms to form distorted KF12 cuboctahedra that share corners with twelve equivalent K(2)F12 cuboctahedra, faces with six equivalent K(1)F12 cuboctahedra, and faces with four equivalent Si(1)F6 octahedra. Si(1) is bonded to three equivalent F(1) and three equivalent F(2) atoms to form SiF6 octahedra that share corners with three equivalent K(1)F12 cuboctahedra, faces with three equivalent K(1)F12 cuboctahedra, and faces with four equivalent K(2)F12 cuboctahedra. There are two inequivalent F sites. In the first F site, F(1) is bonded in a single-bond geometry to two equivalent K(1), two equivalent K(2), and one Si(1) atom. In the second F site, F(2) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Si(1) atom.
K2SiF6 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to six equivalent F(1) and six equivalent F(2) atoms to form distorted KF12 cuboctahedra that share corners with six equivalent K(1)F12 cuboctahedra, corners with three equivalent Si(1)F6 octahedra, faces with two equivalent K(1)F12 cuboctahedra, faces with six equivalent K(2)F12 cuboctahedra, and faces with three equivalent Si(1)F6 octahedra. The corner-sharing octahedral tilt angles are 15°. All K(1)-F(1) bond lengths are 2.84 Å. There are three shorter (2.79 Å) and three longer (3.04 Å) K(1)-F(2) bond lengths. In the second K site, K(2) is bonded to six equivalent F(1) and six equivalent F(2) atoms to form distorted KF12 cuboctahedra that share corners with twelve equivalent K(2)F12 cuboctahedra, faces with six equivalent K(1)F12 cuboctahedra, and faces with four equivalent Si(1)F6 octahedra. There are three shorter (2.76 Å) and three longer (2.85 Å) K(2)-F(1) bond lengths. All K(2)-F(2) bond lengths are 2.80 Å. Si(1) is bonded to three equivalent F(1) and three equivalent F(2) atoms to form SiF6 octahedra that share corners with three equivalent K(1)F12 cuboctahedra, faces with three equivalent K(1)F12 cuboctahedra, and faces with four equivalent K(2)F12 cuboctahedra. All Si(1)-F(1) bond lengths are 1.70 Å. All Si(1)-F(2) bond lengths are 1.70 Å. There are two inequivalent F sites. In the first F site, F(1) is bonded in a single-bond geometry to two equivalent K(1), two equivalent K(2), and one Si(1) atom. In the second F site, F(2) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Si(1) atom.