MgNb2V2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent V(1)O4 tetrahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with two equivalent V(2)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(4) atoms. In the second Nb site, Nb(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent V(2)O6 octahedra, corners with two equivalent V(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent V(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are two inequivalent V sites. In the first V site, V(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted VO4 tetrahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent V(2)O6 octahedra, and corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-71°. In the second V site, V(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form VO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent V(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Nb(1), one Nb(2), and one V(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Nb(2), and one V(2) atom. In the third O site, O(3) is bonded to one Mg(1), one Nb(2), one V(1), and one V(2) atom to form distorted corner-sharing OMgNbV2 tetrahedra. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one Nb(1), and one V(1) atom.
MgNb2V2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent V(1)O4 tetrahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with two equivalent V(2)O6 octahedra. Both Mg(1)-O(2) bond lengths are 2.13 Å. Both Mg(1)-O(3) bond lengths are 2.12 Å. Both Mg(1)-O(4) bond lengths are 2.12 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(4) atoms. Both Nb(1)-O(1) bond lengths are 1.94 Å. Both Nb(1)-O(4) bond lengths are 1.86 Å. In the second Nb site, Nb(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent V(2)O6 octahedra, corners with two equivalent V(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent V(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. Both Nb(2)-O(1) bond lengths are 2.15 Å. Both Nb(2)-O(2) bond lengths are 1.96 Å. Both Nb(2)-O(3) bond lengths are 2.00 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted VO4 tetrahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent V(2)O6 octahedra, and corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-71°. Both V(1)-O(3) bond lengths are 2.17 Å. Both V(1)-O(4) bond lengths are 2.05 Å. In the second V site, V(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form VO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent V(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. Both V(2)-O(1) bond lengths are 2.19 Å. Both V(2)-O(2) bond lengths are 2.07 Å. Both V(2)-O(3) bond lengths are 2.24 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Nb(1), one Nb(2), and one V(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Nb(2), and one V(2) atom. In the third O site, O(3) is bonded to one Mg(1), one Nb(2), one V(1), and one V(2) atom to form distorted corner-sharing OMgNbV2 tetrahedra. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one Nb(1), and one V(1) atom.