RbUSeO8 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(4), two equivalent O(7), and two equivalent O(8) atoms. U(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and two equivalent O(3) atoms to form distorted UO7 pentagonal bipyramids that share corners with two equivalent U(1)O7 pentagonal bipyramids and corners with two equivalent Se(1)O4 tetrahedra. Se(1) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent U(1)O7 pentagonal bipyramids. There are eight inequivalent O sites. In the first O site, O(6) is bonded in a single-bond geometry to one U(1) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Rb(1) and one Se(1) atom. In the third O site, O(8) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one Se(1) atom. In the fourth O site, O(1) is bonded in a distorted single-bond geometry to one Rb(1) and one U(1) atom. In the fifth O site, O(2) is bonded in a single-bond geometry to two equivalent Rb(1) and one U(1) atom. In the sixth O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent U(1) atoms. In the seventh O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Rb(1), one U(1), and one Se(1) atom. In the eighth O site, O(5) is bonded in a bent 150 degrees geometry to one U(1) and one Se(1) atom.
RbUSeO8 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(4), two equivalent O(7), and two equivalent O(8) atoms. The Rb(1)-O(1) bond length is 2.96 Å. There is one shorter (3.11 Å) and one longer (3.22 Å) Rb(1)-O(2) bond length. There is one shorter (3.22 Å) and one longer (3.40 Å) Rb(1)-O(4) bond length. There is one shorter (2.83 Å) and one longer (3.00 Å) Rb(1)-O(7) bond length. There is one shorter (2.98 Å) and one longer (3.11 Å) Rb(1)-O(8) bond length. U(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and two equivalent O(3) atoms to form distorted UO7 pentagonal bipyramids that share corners with two equivalent U(1)O7 pentagonal bipyramids and corners with two equivalent Se(1)O4 tetrahedra. The U(1)-O(1) bond length is 1.82 Å. The U(1)-O(2) bond length is 1.84 Å. The U(1)-O(4) bond length is 2.36 Å. The U(1)-O(5) bond length is 2.31 Å. The U(1)-O(6) bond length is 2.28 Å. There is one shorter (2.25 Å) and one longer (2.34 Å) U(1)-O(3) bond length. Se(1) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent U(1)O7 pentagonal bipyramids. The Se(1)-O(4) bond length is 1.71 Å. The Se(1)-O(5) bond length is 1.70 Å. The Se(1)-O(7) bond length is 1.64 Å. The Se(1)-O(8) bond length is 1.65 Å. There are eight inequivalent O sites. In the first O site, O(6) is bonded in a single-bond geometry to one U(1) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Rb(1) and one Se(1) atom. In the third O site, O(8) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one Se(1) atom. In the fourth O site, O(1) is bonded in a distorted single-bond geometry to one Rb(1) and one U(1) atom. In the fifth O site, O(2) is bonded in a single-bond geometry to two equivalent Rb(1) and one U(1) atom. In the sixth O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent U(1) atoms. In the seventh O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Rb(1), one U(1), and one Se(1) atom. In the eighth O site, O(5) is bonded in a bent 150 degrees geometry to one U(1) and one Se(1) atom.