Na4MgV4O10 crystallizes in the triclinic P1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(1), one O(5), one O(7), and one O(9) atom. In the second Na site, Na(2) is bonded in a 3-coordinate geometry to one O(10), one O(2), one O(6), and one O(8) atom. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(5), and one O(7) atom. In the fourth Na site, Na(4) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(8), and one O(9) atom. Mg(1) is bonded in a square co-planar geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form VO6 octahedra that share corners with four equivalent V(2)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra, and  a cornercorner with one V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 7°. In the second V site, V(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form VO6 octahedra that share corners with four equivalent V(1)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra, and  a cornercorner with one V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 7°. In the third V site, V(3) is bonded to one O(10), one O(5), one O(8), and one O(9) atom to form VO4 tetrahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, and corners with two equivalent V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-41°. In the fourth V site, V(4) is bonded to one O(10), one O(6), one O(7), and one O(9) atom to form VO4 tetrahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, and corners with two equivalent V(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-41°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(2), one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom. In the third O site, O(3) is bonded to one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom to form distorted ONa2MgV2 trigonal bipyramids that share  a cornercorner with one O(10)Na2V2 tetrahedra,  a cornercorner with one O(9)Na2V2 tetrahedra,  an edgeedge with one O(4)Na2MgV2 trigonal bipyramid, and  a faceface with one O(4)Na2MgV2 trigonal bipyramid. In the fourth O site, O(4) is bonded to one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom to form distorted ONa2MgV2 trigonal bipyramids that share  a cornercorner with one O(10)Na2V2 tetrahedra,  a cornercorner with one O(9)Na2V2 tetrahedra,  an edgeedge with one O(3)Na2MgV2 trigonal bipyramid, and  a faceface with one O(3)Na2MgV2 trigonal bipyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one V(1), and one V(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one V(1), and one V(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one V(2), and one V(4) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one V(2), and one V(3) atom. In the ninth O site, O(9) is bonded to one Na(1), one Na(4), one V(3), and one V(4) atom to form distorted ONa2V2 tetrahedra that share corners with two equivalent O(10)Na2V2 tetrahedra,  a cornercorner with one O(3)Na2MgV2 trigonal bipyramid, and  a cornercorner with one O(4)Na2MgV2 trigonal bipyramid. In the tenth O site, O(10) is bonded to one Na(2), one Na(3), one V(3), and one V(4) atom to form distorted ONa2V2 tetrahedra that share corners with two equivalent O(9)Na2V2 tetrahedra,  a cornercorner with one O(3)Na2MgV2 trigonal bipyramid, and  a cornercorner with one O(4)Na2MgV2 trigonal bipyramid.
Na4MgV4O10 crystallizes in the triclinic P1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(1), one O(5), one O(7), and one O(9) atom. The Na(1)-O(1) bond length is 2.61 Å. The Na(1)-O(5) bond length is 2.25 Å. The Na(1)-O(7) bond length is 2.22 Å. The Na(1)-O(9) bond length is 2.25 Å. In the second Na site, Na(2) is bonded in a 3-coordinate geometry to one O(10), one O(2), one O(6), and one O(8) atom. The Na(2)-O(10) bond length is 2.24 Å. The Na(2)-O(2) bond length is 2.62 Å. The Na(2)-O(6) bond length is 2.25 Å. The Na(2)-O(8) bond length is 2.22 Å. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(5), and one O(7) atom. The Na(3)-O(1) bond length is 2.54 Å. The Na(3)-O(10) bond length is 2.39 Å. The Na(3)-O(2) bond length is 2.77 Å. The Na(3)-O(3) bond length is 2.42 Å. The Na(3)-O(4) bond length is 2.45 Å. The Na(3)-O(5) bond length is 2.56 Å. The Na(3)-O(7) bond length is 2.77 Å. In the fourth Na site, Na(4) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(8), and one O(9) atom. The Na(4)-O(1) bond length is 2.78 Å. The Na(4)-O(2) bond length is 2.55 Å. The Na(4)-O(3) bond length is 2.45 Å. The Na(4)-O(4) bond length is 2.42 Å. The Na(4)-O(6) bond length is 2.56 Å. The Na(4)-O(8) bond length is 2.77 Å. The Na(4)-O(9) bond length is 2.39 Å. Mg(1) is bonded in a square co-planar geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Mg(1)-O(1) bond length is 1.99 Å. The Mg(1)-O(2) bond length is 1.99 Å. The Mg(1)-O(3) bond length is 1.98 Å. The Mg(1)-O(4) bond length is 1.98 Å. There are four inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form VO6 octahedra that share corners with four equivalent V(2)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra, and  a cornercorner with one V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 7°. The V(1)-O(1) bond length is 2.06 Å. The V(1)-O(2) bond length is 2.06 Å. The V(1)-O(3) bond length is 2.03 Å. The V(1)-O(4) bond length is 2.03 Å. The V(1)-O(5) bond length is 2.19 Å. The V(1)-O(6) bond length is 2.19 Å. In the second V site, V(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form VO6 octahedra that share corners with four equivalent V(1)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra, and  a cornercorner with one V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 7°. The V(2)-O(1) bond length is 2.05 Å. The V(2)-O(2) bond length is 2.05 Å. The V(2)-O(3) bond length is 2.07 Å. The V(2)-O(4) bond length is 2.07 Å. The V(2)-O(7) bond length is 2.15 Å. The V(2)-O(8) bond length is 2.15 Å. In the third V site, V(3) is bonded to one O(10), one O(5), one O(8), and one O(9) atom to form VO4 tetrahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, and corners with two equivalent V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-41°. The V(3)-O(10) bond length is 1.89 Å. The V(3)-O(5) bond length is 1.76 Å. The V(3)-O(8) bond length is 1.77 Å. The V(3)-O(9) bond length is 1.91 Å. In the fourth V site, V(4) is bonded to one O(10), one O(6), one O(7), and one O(9) atom to form VO4 tetrahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, and corners with two equivalent V(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-41°. The V(4)-O(10) bond length is 1.91 Å. The V(4)-O(6) bond length is 1.76 Å. The V(4)-O(7) bond length is 1.77 Å. The V(4)-O(9) bond length is 1.89 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(2), one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom. In the third O site, O(3) is bonded to one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom to form distorted ONa2MgV2 trigonal bipyramids that share  a cornercorner with one O(10)Na2V2 tetrahedra,  a cornercorner with one O(9)Na2V2 tetrahedra,  an edgeedge with one O(4)Na2MgV2 trigonal bipyramid, and  a faceface with one O(4)Na2MgV2 trigonal bipyramid. In the fourth O site, O(4) is bonded to one Na(3), one Na(4), one Mg(1), one V(1), and one V(2) atom to form distorted ONa2MgV2 trigonal bipyramids that share  a cornercorner with one O(10)Na2V2 tetrahedra,  a cornercorner with one O(9)Na2V2 tetrahedra,  an edgeedge with one O(3)Na2MgV2 trigonal bipyramid, and  a faceface with one O(3)Na2MgV2 trigonal bipyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one V(1), and one V(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one V(1), and one V(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one V(2), and one V(4) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one V(2), and one V(3) atom. In the ninth O site, O(9) is bonded to one Na(1), one Na(4), one V(3), and one V(4) atom to form distorted ONa2V2 tetrahedra that share corners with two equivalent O(10)Na2V2 tetrahedra,  a cornercorner with one O(3)Na2MgV2 trigonal bipyramid, and  a cornercorner with one O(4)Na2MgV2 trigonal bipyramid. In the tenth O site, O(10) is bonded to one Na(2), one Na(3), one V(3), and one V(4) atom to form distorted ONa2V2 tetrahedra that share corners with two equivalent O(9)Na2V2 tetrahedra,  a cornercorner with one O(3)Na2MgV2 trigonal bipyramid, and  a cornercorner with one O(4)Na2MgV2 trigonal bipyramid.