BaU3W3(SeO7)2 crystallizes in the orthorhombic Pmn2_1 space group. Ba(1) is bonded in a 6-coordinate geometry to one O(2), one O(8), two equivalent O(3), and two equivalent O(5) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded to one O(2), one O(4), one O(6), one O(8), two equivalent O(1), and two equivalent O(9) atoms to form distorted edge-sharing UO8 hexagonal bipyramids. In the second U site, U(2) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(9) atom to form distorted UO7 pentagonal bipyramids that share edges with two equivalent U(1)O8 hexagonal bipyramids and  an edgeedge with one U(2)O7 pentagonal bipyramid. There are two inequivalent W sites. In the first W site, W(1) is bonded in a single-bond geometry to one O(7) atom. In the second W site, W(2) is bonded in a bent 120 degrees geometry to one O(2) and one O(8) atom. Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(7), and one O(9) atom. There are nine inequivalent O sites. In the first O site, O(6) is bonded in a trigonal planar geometry to one U(1) and two equivalent U(2) atoms. In the second O site, O(7) is bonded in a trigonal planar geometry to one U(2), one W(1), and one Se(1) atom. In the third O site, O(8) is bonded in a 3-coordinate geometry to one Ba(1), one U(1), and one W(2) atom. In the fourth O site, O(9) is bonded in a 3-coordinate geometry to one U(1), one U(2), and one Se(1) atom. In the fifth O site, O(1) is bonded in a 3-coordinate geometry to one U(1), one U(2), and one Se(1) atom. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one U(1), and one W(2) atom. In the seventh O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ba(1) and one U(2) atom. In the eighth O site, O(4) is bonded in a distorted trigonal planar geometry to one U(1) and two equivalent U(2) atoms. In the ninth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Ba(1) and one U(2) atom.
BaU3W3(SeO7)2 crystallizes in the orthorhombic Pmn2_1 space group. Ba(1) is bonded in a 6-coordinate geometry to one O(2), one O(8), two equivalent O(3), and two equivalent O(5) atoms. The Ba(1)-O(2) bond length is 3.06 Å. The Ba(1)-O(8) bond length is 3.05 Å. Both Ba(1)-O(3) bond lengths are 2.79 Å. Both Ba(1)-O(5) bond lengths are 2.81 Å. There are two inequivalent U sites. In the first U site, U(1) is bonded to one O(2), one O(4), one O(6), one O(8), two equivalent O(1), and two equivalent O(9) atoms to form distorted edge-sharing UO8 hexagonal bipyramids. The U(1)-O(2) bond length is 2.05 Å. The U(1)-O(4) bond length is 2.25 Å. The U(1)-O(6) bond length is 2.22 Å. The U(1)-O(8) bond length is 2.05 Å. Both U(1)-O(1) bond lengths are 2.71 Å. Both U(1)-O(9) bond lengths are 2.60 Å. In the second U site, U(2) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(9) atom to form distorted UO7 pentagonal bipyramids that share edges with two equivalent U(1)O8 hexagonal bipyramids and  an edgeedge with one U(2)O7 pentagonal bipyramid. The U(2)-O(1) bond length is 2.42 Å. The U(2)-O(3) bond length is 1.90 Å. The U(2)-O(4) bond length is 2.28 Å. The U(2)-O(5) bond length is 1.89 Å. The U(2)-O(6) bond length is 2.27 Å. The U(2)-O(7) bond length is 2.49 Å. The U(2)-O(9) bond length is 2.46 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded in a single-bond geometry to one O(7) atom. The W(1)-O(7) bond length is 2.22 Å. In the second W site, W(2) is bonded in a bent 120 degrees geometry to one O(2) and one O(8) atom. The W(2)-O(2) bond length is 1.97 Å. The W(2)-O(8) bond length is 1.99 Å. Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(7), and one O(9) atom. The Se(1)-O(1) bond length is 1.72 Å. The Se(1)-O(7) bond length is 1.80 Å. The Se(1)-O(9) bond length is 1.72 Å. There are nine inequivalent O sites. In the first O site, O(6) is bonded in a trigonal planar geometry to one U(1) and two equivalent U(2) atoms. In the second O site, O(7) is bonded in a trigonal planar geometry to one U(2), one W(1), and one Se(1) atom. In the third O site, O(8) is bonded in a 3-coordinate geometry to one Ba(1), one U(1), and one W(2) atom. In the fourth O site, O(9) is bonded in a 3-coordinate geometry to one U(1), one U(2), and one Se(1) atom. In the fifth O site, O(1) is bonded in a 3-coordinate geometry to one U(1), one U(2), and one Se(1) atom. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one U(1), and one W(2) atom. In the seventh O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ba(1) and one U(2) atom. In the eighth O site, O(4) is bonded in a distorted trigonal planar geometry to one U(1) and two equivalent U(2) atoms. In the ninth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Ba(1) and one U(2) atom.