K3UF7 crystallizes in the tetragonal I4_1/a space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to two equivalent F(3) and four equivalent F(2) atoms to form KF6 octahedra that share corners with six equivalent U(1)F7 pentagonal bipyramids. In the second K site, K(2) is bonded to four equivalent F(1) and four equivalent F(4) atoms to form distorted KF8 hexagonal bipyramids that share corners with four equivalent U(1)F7 pentagonal bipyramids and edges with two equivalent U(1)F7 pentagonal bipyramids. In the third K site, K(3) is bonded in a 9-coordinate geometry to two equivalent F(1), two equivalent F(3), two equivalent F(4), and three equivalent F(2) atoms. U(1) is bonded to one F(3), two equivalent F(1), two equivalent F(2), and two equivalent F(4) atoms to form UF7 pentagonal bipyramids that share corners with two equivalent K(2)F8 hexagonal bipyramids, corners with three equivalent K(1)F6 octahedra, and  an edgeedge with one K(2)F8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 0-37°. There are four inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to one K(2), two equivalent K(3), and one U(1) atom. In the second F site, F(2) is bonded in a 5-coordinate geometry to one K(1), three equivalent K(3), and one U(1) atom. In the third F site, F(3) is bonded in a 2-coordinate geometry to one K(1), four equivalent K(3), and one U(1) atom. In the fourth F site, F(4) is bonded to one K(2), two equivalent K(3), and one U(1) atom to form a mixture of corner and edge-sharing FK3U tetrahedra.
K3UF7 crystallizes in the tetragonal I4_1/a space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to two equivalent F(3) and four equivalent F(2) atoms to form KF6 octahedra that share corners with six equivalent U(1)F7 pentagonal bipyramids. Both K(1)-F(3) bond lengths are 2.67 Å. All K(1)-F(2) bond lengths are 2.67 Å. In the second K site, K(2) is bonded to four equivalent F(1) and four equivalent F(4) atoms to form distorted KF8 hexagonal bipyramids that share corners with four equivalent U(1)F7 pentagonal bipyramids and edges with two equivalent U(1)F7 pentagonal bipyramids. All K(2)-F(1) bond lengths are 2.71 Å. All K(2)-F(4) bond lengths are 2.79 Å. In the third K site, K(3) is bonded in a 9-coordinate geometry to two equivalent F(1), two equivalent F(3), two equivalent F(4), and three equivalent F(2) atoms. There is one shorter (2.94 Å) and one longer (2.95 Å) K(3)-F(1) bond length. There is one shorter (3.04 Å) and one longer (3.25 Å) K(3)-F(3) bond length. There is one shorter (2.66 Å) and one longer (2.74 Å) K(3)-F(4) bond length. There are a spread of K(3)-F(2) bond distances ranging from 2.63-3.17 Å. U(1) is bonded to one F(3), two equivalent F(1), two equivalent F(2), and two equivalent F(4) atoms to form UF7 pentagonal bipyramids that share corners with two equivalent K(2)F8 hexagonal bipyramids, corners with three equivalent K(1)F6 octahedra, and  an edgeedge with one K(2)F8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 0-37°. The U(1)-F(3) bond length is 2.28 Å. Both U(1)-F(1) bond lengths are 2.18 Å. Both U(1)-F(2) bond lengths are 2.30 Å. Both U(1)-F(4) bond lengths are 2.26 Å. There are four inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to one K(2), two equivalent K(3), and one U(1) atom. In the second F site, F(2) is bonded in a 5-coordinate geometry to one K(1), three equivalent K(3), and one U(1) atom. In the third F site, F(3) is bonded in a 2-coordinate geometry to one K(1), four equivalent K(3), and one U(1) atom. In the fourth F site, F(4) is bonded to one K(2), two equivalent K(3), and one U(1) atom to form a mixture of corner and edge-sharing FK3U tetrahedra.