Ba2AsSe4O3 crystallizes in the monoclinic Cm space group. Ba(1) is bonded in a 3-coordinate geometry to two equivalent Se(1), three equivalent Se(2), one O(1), and two equivalent O(2) atoms. As(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(1) and two equivalent Se(2) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to four equivalent Ba(1) and one As(1) atom to form distorted corner-sharing SeBa4As trigonal bipyramids. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Ba(1), one As(1), and one Se(3) atom. In the third Se site, Se(3) is bonded in a single-bond geometry to two equivalent Se(2) and one O(1) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to two equivalent Ba(1) and one Se(3) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Ba(1) and one O(2) atom.
Ba2AsSe4O3 crystallizes in the monoclinic Cm space group. Ba(1) is bonded in a 3-coordinate geometry to two equivalent Se(1), three equivalent Se(2), one O(1), and two equivalent O(2) atoms. There is one shorter (3.33 Å) and one longer (3.42 Å) Ba(1)-Se(1) bond length. There are a spread of Ba(1)-Se(2) bond distances ranging from 3.47-3.85 Å. The Ba(1)-O(1) bond length is 2.59 Å. Both Ba(1)-O(2) bond lengths are 2.84 Å. As(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(1) and two equivalent Se(2) atoms. The As(1)-Se(1) bond length is 2.43 Å. Both As(1)-Se(2) bond lengths are 2.48 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to four equivalent Ba(1) and one As(1) atom to form distorted corner-sharing SeBa4As trigonal bipyramids. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Ba(1), one As(1), and one Se(3) atom. The Se(2)-Se(3) bond length is 2.69 Å. In the third Se site, Se(3) is bonded in a single-bond geometry to two equivalent Se(2) and one O(1) atom. The Se(3)-O(1) bond length is 1.76 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to two equivalent Ba(1) and one Se(3) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Ba(1) and one O(2) atom. The O(2)-O(2) bond length is 1.35 Å.