K3SiF7 crystallizes in the tetragonal P4/mbm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 10-coordinate geometry to two equivalent F(2), two equivalent F(3), and six equivalent F(1) atoms. In the second K site, K(2) is bonded to two equivalent F(2) and four equivalent F(3) atoms to form KF6 octahedra that share corners with four equivalent Si(1)F6 octahedra and corners with six equivalent K(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 0-70°. Si(1) is bonded to two equivalent F(3) and four equivalent F(1) atoms to form SiF6 octahedra that share corners with four equivalent K(2)F6 octahedra. The corner-sharing octahedral tilt angles are 70°. There are three inequivalent F sites. In the first F site, F(1) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Si(1) atom. In the second F site, F(2) is bonded to two equivalent K(2) and four equivalent K(1) atoms to form corner-sharing FK6 octahedra. The corner-sharing octahedral tilt angles range from 0-26°. In the third F site, F(3) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Si(1) atom.
K3SiF7 crystallizes in the tetragonal P4/mbm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 10-coordinate geometry to two equivalent F(2), two equivalent F(3), and six equivalent F(1) atoms. Both K(1)-F(2) bond lengths are 2.76 Å. Both K(1)-F(3) bond lengths are 2.78 Å. There are two shorter (2.62 Å) and four longer (2.84 Å) K(1)-F(1) bond lengths. In the second K site, K(2) is bonded to two equivalent F(2) and four equivalent F(3) atoms to form KF6 octahedra that share corners with four equivalent Si(1)F6 octahedra and corners with six equivalent K(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 0-70°. Both K(2)-F(2) bond lengths are 2.75 Å. All K(2)-F(3) bond lengths are 2.87 Å. Si(1) is bonded to two equivalent F(3) and four equivalent F(1) atoms to form SiF6 octahedra that share corners with four equivalent K(2)F6 octahedra. The corner-sharing octahedral tilt angles are 70°. Both Si(1)-F(3) bond lengths are 1.69 Å. All Si(1)-F(1) bond lengths are 1.70 Å. There are three inequivalent F sites. In the first F site, F(1) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Si(1) atom. In the second F site, F(2) is bonded to two equivalent K(2) and four equivalent K(1) atoms to form corner-sharing FK6 octahedra. The corner-sharing octahedral tilt angles range from 0-26°. In the third F site, F(3) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Si(1) atom.