KU2SbSe8 crystallizes in the monoclinic Cm space group. K(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms. U(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms. Sb(1) is bonded in a see-saw-like geometry to one Se(2), one Se(3), and two equivalent Se(5) atoms. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent U(1), and one Se(4) atom. In the second Se site, Se(2) is bonded to one K(1), two equivalent U(1), and one Sb(1) atom to form distorted corner-sharing SeKU2Sb trigonal pyramids. In the third Se site, Se(3) is bonded to one K(1), two equivalent U(1), and one Sb(1) atom to form distorted corner-sharing SeKU2Sb trigonal pyramids. In the fourth Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to one K(1), two equivalent U(1), and one Se(1) atom. In the fifth Se site, Se(5) is bonded in a rectangular see-saw-like geometry to one K(1), two equivalent U(1), and one Sb(1) atom.
KU2SbSe8 crystallizes in the monoclinic Cm space group. K(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms. The K(1)-Se(2) bond length is 3.45 Å. The K(1)-Se(3) bond length is 3.46 Å. Both K(1)-Se(1) bond lengths are 3.51 Å. Both K(1)-Se(4) bond lengths are 3.55 Å. Both K(1)-Se(5) bond lengths are 3.34 Å. U(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms. The U(1)-Se(2) bond length is 2.99 Å. The U(1)-Se(3) bond length is 2.98 Å. There is one shorter (2.93 Å) and one longer (2.97 Å) U(1)-Se(1) bond length. There is one shorter (2.90 Å) and one longer (2.94 Å) U(1)-Se(4) bond length. Both U(1)-Se(5) bond lengths are 2.86 Å. Sb(1) is bonded in a see-saw-like geometry to one Se(2), one Se(3), and two equivalent Se(5) atoms. The Sb(1)-Se(2) bond length is 2.61 Å. The Sb(1)-Se(3) bond length is 2.61 Å. Both Sb(1)-Se(5) bond lengths are 2.84 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent U(1), and one Se(4) atom. The Se(1)-Se(4) bond length is 2.41 Å. In the second Se site, Se(2) is bonded to one K(1), two equivalent U(1), and one Sb(1) atom to form distorted corner-sharing SeKU2Sb trigonal pyramids. In the third Se site, Se(3) is bonded to one K(1), two equivalent U(1), and one Sb(1) atom to form distorted corner-sharing SeKU2Sb trigonal pyramids. In the fourth Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to one K(1), two equivalent U(1), and one Se(1) atom. In the fifth Se site, Se(5) is bonded in a rectangular see-saw-like geometry to one K(1), two equivalent U(1), and one Sb(1) atom.