MgV3CoO8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(7) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra, corners with two equivalent V(1)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra,  an edgeedge with one V(2)O4 tetrahedra, and  an edgeedge with one V(3)O4 tetrahedra. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(3), one O(7), and one O(8) atom to form VO4 tetrahedra that share corners with two equivalent V(3)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. In the second V site, V(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form distorted VO4 tetrahedra that share corners with two equivalent V(3)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. In the third V site, V(3) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form VO4 tetrahedra that share corners with two equivalent V(1)O4 tetrahedra, corners with two equivalent V(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. Co(1) is bonded to one O(1), one O(2), one O(6), and one O(8) atom to form CoO4 tetrahedra that share corners with two equivalent V(1)O4 tetrahedra, corners with two equivalent V(2)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one V(1), and one Co(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one Co(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one V(1) and one V(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one V(3) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one V(2) and one Co(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one V(1), and one V(3) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one V(1) and one Co(1) atom.
MgV3CoO8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(7) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra, corners with two equivalent V(1)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra,  an edgeedge with one V(2)O4 tetrahedra, and  an edgeedge with one V(3)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.05 Å. The Mg(1)-O(2) bond length is 2.03 Å. The Mg(1)-O(4) bond length is 2.09 Å. The Mg(1)-O(5) bond length is 2.21 Å. The Mg(1)-O(7) bond length is 2.09 Å. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(3), one O(7), and one O(8) atom to form VO4 tetrahedra that share corners with two equivalent V(3)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The V(1)-O(1) bond length is 1.84 Å. The V(1)-O(3) bond length is 1.87 Å. The V(1)-O(7) bond length is 1.88 Å. The V(1)-O(8) bond length is 1.72 Å. In the second V site, V(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form distorted VO4 tetrahedra that share corners with two equivalent V(3)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The V(2)-O(2) bond length is 1.80 Å. The V(2)-O(4) bond length is 1.87 Å. The V(2)-O(5) bond length is 1.93 Å. The V(2)-O(6) bond length is 1.72 Å. In the third V site, V(3) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form VO4 tetrahedra that share corners with two equivalent V(1)O4 tetrahedra, corners with two equivalent V(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The V(3)-O(3) bond length is 1.76 Å. The V(3)-O(4) bond length is 1.85 Å. The V(3)-O(5) bond length is 1.79 Å. The V(3)-O(7) bond length is 1.89 Å. Co(1) is bonded to one O(1), one O(2), one O(6), and one O(8) atom to form CoO4 tetrahedra that share corners with two equivalent V(1)O4 tetrahedra, corners with two equivalent V(2)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The Co(1)-O(1) bond length is 2.01 Å. The Co(1)-O(2) bond length is 2.05 Å. The Co(1)-O(6) bond length is 1.96 Å. The Co(1)-O(8) bond length is 1.96 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one V(1), and one Co(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one Co(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one V(1) and one V(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one V(3) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one V(2) and one Co(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one V(1), and one V(3) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one V(1) and one Co(1) atom.