Ba3MgV2O8 crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(6), one O(7), one O(8), and two equivalent O(5) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and two equivalent O(8) atoms. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(8) atom. Mg(1) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form distorted MgO4 tetrahedra that share  an edgeedge with one V(1)O4 tetrahedra and  an edgeedge with one V(2)O4 tetrahedra. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form VO4 tetrahedra that share  an edgeedge with one Mg(1)O4 tetrahedra. In the second V site, V(2) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form VO4 tetrahedra that share  an edgeedge with one Mg(1)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ba(2), one Ba(3), one Mg(1), and one V(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), one Ba(3), one Mg(1), and one V(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), one Ba(2), one Ba(3), and one V(1) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to one Ba(1), one Ba(2), one Mg(1), and one V(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(3), two equivalent Ba(1), and one V(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), one Ba(2), one Ba(3), and one V(2) atom. In the seventh O site, O(7) is bonded in a distorted L-shaped geometry to one Ba(1), one Ba(2), one Mg(1), and one V(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(3), two equivalent Ba(2), and one V(2) atom.
Ba3MgV2O8 crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(6), one O(7), one O(8), and two equivalent O(5) atoms. The Ba(1)-O(2) bond length is 2.72 Å. The Ba(1)-O(3) bond length is 2.79 Å. The Ba(1)-O(4) bond length is 2.94 Å. The Ba(1)-O(6) bond length is 2.73 Å. The Ba(1)-O(7) bond length is 2.90 Å. The Ba(1)-O(8) bond length is 2.89 Å. There is one shorter (2.93 Å) and one longer (3.39 Å) Ba(1)-O(5) bond length. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and two equivalent O(8) atoms. The Ba(2)-O(1) bond length is 2.72 Å. The Ba(2)-O(3) bond length is 2.73 Å. The Ba(2)-O(4) bond length is 2.89 Å. The Ba(2)-O(5) bond length is 2.89 Å. The Ba(2)-O(6) bond length is 2.79 Å. The Ba(2)-O(7) bond length is 2.95 Å. There is one shorter (2.92 Å) and one longer (3.40 Å) Ba(2)-O(8) bond length. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(8) atom. The Ba(3)-O(1) bond length is 2.79 Å. The Ba(3)-O(2) bond length is 2.79 Å. The Ba(3)-O(3) bond length is 2.77 Å. The Ba(3)-O(5) bond length is 2.68 Å. The Ba(3)-O(6) bond length is 2.77 Å. The Ba(3)-O(8) bond length is 2.68 Å. Mg(1) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form distorted MgO4 tetrahedra that share  an edgeedge with one V(1)O4 tetrahedra and  an edgeedge with one V(2)O4 tetrahedra. The Mg(1)-O(1) bond length is 1.97 Å. The Mg(1)-O(2) bond length is 1.98 Å. The Mg(1)-O(4) bond length is 1.98 Å. The Mg(1)-O(7) bond length is 1.98 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form VO4 tetrahedra that share  an edgeedge with one Mg(1)O4 tetrahedra. The V(1)-O(1) bond length is 1.89 Å. The V(1)-O(3) bond length is 1.77 Å. The V(1)-O(4) bond length is 1.92 Å. The V(1)-O(5) bond length is 1.79 Å. In the second V site, V(2) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form VO4 tetrahedra that share  an edgeedge with one Mg(1)O4 tetrahedra. The V(2)-O(2) bond length is 1.89 Å. The V(2)-O(6) bond length is 1.77 Å. The V(2)-O(7) bond length is 1.92 Å. The V(2)-O(8) bond length is 1.79 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ba(2), one Ba(3), one Mg(1), and one V(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), one Ba(3), one Mg(1), and one V(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), one Ba(2), one Ba(3), and one V(1) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to one Ba(1), one Ba(2), one Mg(1), and one V(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(3), two equivalent Ba(1), and one V(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), one Ba(2), one Ba(3), and one V(2) atom. In the seventh O site, O(7) is bonded in a distorted L-shaped geometry to one Ba(1), one Ba(2), one Mg(1), and one V(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(3), two equivalent Ba(2), and one V(2) atom.