K3LuF6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms to form KF6 octahedra that share corners with six equivalent Lu(1)F6 octahedra. The corner-sharing octahedral tilt angles range from 32-39°. In the second K site, K(2) is bonded in a 7-coordinate geometry to two equivalent F(1), two equivalent F(2), and three equivalent F(3) atoms. Lu(1) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms to form LuF6 octahedra that share corners with six equivalent K(1)F6 octahedra. The corner-sharing octahedral tilt angles range from 32-39°. There are three inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(2), and one Lu(1) atom. In the second F site, F(2) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent K(2), and one Lu(1) atom. In the third F site, F(3) is bonded in a 5-coordinate geometry to one K(1), three equivalent K(2), and one Lu(1) atom.
K3LuF6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms to form KF6 octahedra that share corners with six equivalent Lu(1)F6 octahedra. The corner-sharing octahedral tilt angles range from 32-39°. Both K(1)-F(1) bond lengths are 2.63 Å. Both K(1)-F(2) bond lengths are 2.59 Å. Both K(1)-F(3) bond lengths are 2.57 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to two equivalent F(1), two equivalent F(2), and three equivalent F(3) atoms. There is one shorter (2.64 Å) and one longer (2.88 Å) K(2)-F(1) bond length. There is one shorter (2.62 Å) and one longer (2.66 Å) K(2)-F(2) bond length. There are a spread of K(2)-F(3) bond distances ranging from 2.64-3.08 Å. Lu(1) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms to form LuF6 octahedra that share corners with six equivalent K(1)F6 octahedra. The corner-sharing octahedral tilt angles range from 32-39°. Both Lu(1)-F(1) bond lengths are 2.11 Å. Both Lu(1)-F(2) bond lengths are 2.10 Å. Both Lu(1)-F(3) bond lengths are 2.10 Å. There are three inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(2), and one Lu(1) atom. In the second F site, F(2) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent K(2), and one Lu(1) atom. In the third F site, F(3) is bonded in a 5-coordinate geometry to one K(1), three equivalent K(2), and one Lu(1) atom.