K4UO5 crystallizes in the triclinic P-1 space group. There are five inequivalent K sites. In the first K site, K(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted KO6 octahedra that share  a cornercorner with one K(5)O6 octahedra, corners with two equivalent U(1)O6 octahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent K(5)O6 octahedra, edges with three equivalent K(2)O6 octahedra, and edges with three equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-25°. In the second K site, K(2) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms to form distorted KO6 octahedra that share  a cornercorner with one K(5)O6 octahedra, corners with three equivalent U(1)O6 octahedra,  an edgeedge with one K(2)O6 octahedra,  an edgeedge with one K(5)O6 octahedra, edges with two equivalent U(1)O6 octahedra, and edges with three equivalent K(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-25°. In the third K site, K(3) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the fifth K site, K(5) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted KO6 octahedra that share corners with two equivalent K(1)O6 octahedra, corners with two equivalent K(2)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with four equivalent K(1)O6 octahedra, and edges with four equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles are 25°. U(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form UO6 octahedra that share corners with two equivalent K(1)O6 octahedra, corners with three equivalent K(2)O6 octahedra,  an edgeedge with one U(1)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with two equivalent K(5)O6 octahedra, and edges with three equivalent K(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-17°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one K(2), one K(3), one K(5), two equivalent K(1), and one U(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one K(4), two equivalent K(2), two equivalent K(3), and one U(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one K(5), and one U(1) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one K(2), one K(5), two equivalent K(1), and two equivalent U(1) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), two equivalent K(3), and one U(1) atom.
K4UO5 crystallizes in the triclinic P-1 space group. There are five inequivalent K sites. In the first K site, K(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted KO6 octahedra that share  a cornercorner with one K(5)O6 octahedra, corners with two equivalent U(1)O6 octahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent K(5)O6 octahedra, edges with three equivalent K(2)O6 octahedra, and edges with three equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-25°. The K(1)-O(3) bond length is 2.72 Å. The K(1)-O(5) bond length is 2.64 Å. There is one shorter (2.70 Å) and one longer (3.04 Å) K(1)-O(1) bond length. There is one shorter (2.70 Å) and one longer (2.95 Å) K(1)-O(4) bond length. In the second K site, K(2) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms to form distorted KO6 octahedra that share  a cornercorner with one K(5)O6 octahedra, corners with three equivalent U(1)O6 octahedra,  an edgeedge with one K(2)O6 octahedra,  an edgeedge with one K(5)O6 octahedra, edges with two equivalent U(1)O6 octahedra, and edges with three equivalent K(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-25°. The K(2)-O(1) bond length is 2.67 Å. The K(2)-O(3) bond length is 3.07 Å. The K(2)-O(4) bond length is 3.11 Å. The K(2)-O(5) bond length is 2.65 Å. There is one shorter (2.64 Å) and one longer (3.14 Å) K(2)-O(2) bond length. In the third K site, K(3) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms. The K(3)-O(1) bond length is 2.75 Å. The K(3)-O(3) bond length is 2.80 Å. There is one shorter (2.68 Å) and one longer (2.81 Å) K(3)-O(2) bond length. There is one shorter (2.70 Å) and one longer (2.72 Å) K(3)-O(5) bond length. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both K(4)-O(2) bond lengths are 2.62 Å. Both K(4)-O(3) bond lengths are 2.66 Å. Both K(4)-O(5) bond lengths are 3.30 Å. In the fifth K site, K(5) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted KO6 octahedra that share corners with two equivalent K(1)O6 octahedra, corners with two equivalent K(2)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with four equivalent K(1)O6 octahedra, and edges with four equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles are 25°. Both K(5)-O(1) bond lengths are 2.71 Å. Both K(5)-O(3) bond lengths are 2.72 Å. Both K(5)-O(4) bond lengths are 2.66 Å. U(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form UO6 octahedra that share corners with two equivalent K(1)O6 octahedra, corners with three equivalent K(2)O6 octahedra,  an edgeedge with one U(1)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with two equivalent K(5)O6 octahedra, and edges with three equivalent K(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-17°. The U(1)-O(1) bond length is 2.03 Å. The U(1)-O(2) bond length is 2.08 Å. The U(1)-O(3) bond length is 2.03 Å. The U(1)-O(5) bond length is 2.06 Å. There is one shorter (2.24 Å) and one longer (2.27 Å) U(1)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one K(2), one K(3), one K(5), two equivalent K(1), and one U(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one K(4), two equivalent K(2), two equivalent K(3), and one U(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one K(5), and one U(1) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one K(2), one K(5), two equivalent K(1), and two equivalent U(1) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), two equivalent K(3), and one U(1) atom.