MgV2Ni(TeO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(5), one O(6), one O(7), and one O(9) atom to form distorted MgO5 square pyramids that share corners with two equivalent V(2)O6 octahedra,  a cornercorner with one Ni(1)O5 square pyramid, and  a faceface with one V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-61°. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(10), one O(4), one O(5), one O(7), and one O(9) atom to form VO6 octahedra that share corners with three equivalent Ni(1)O5 square pyramids, edges with two equivalent V(2)O6 octahedra, and  a faceface with one Mg(1)O5 square pyramid. In the second V site, V(2) is bonded to one O(1), one O(10), one O(2), one O(4), one O(6), and one O(7) atom to form VO6 octahedra that share corners with two equivalent Mg(1)O5 square pyramids, corners with three equivalent Ni(1)O5 square pyramids, and edges with two equivalent V(1)O6 octahedra. Ni(1) is bonded to one O(1), one O(10), one O(2), one O(8), and one O(9) atom to form NiO5 square pyramids that share corners with three equivalent V(1)O6 octahedra, corners with three equivalent V(2)O6 octahedra, and  a cornercorner with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 47-56°. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a 5-coordinate geometry to one O(3), one O(6), one O(7), one O(8), and one O(9) atom. In the second Te site, Te(2) is bonded in a 3-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and one O(8) atom. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one Ni(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one V(2), one Ni(1), and one Te(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Te(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one V(1), one V(2), and one Te(2) atom. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Mg(1), one V(1), and one Te(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one Te(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Mg(1), one V(1), one V(2), and one Te(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ni(1), one Te(1), and one Te(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one V(1), one Ni(1), and one Te(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one Ni(1) atom.
MgV2Ni(TeO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(5), one O(6), one O(7), and one O(9) atom to form distorted MgO5 square pyramids that share corners with two equivalent V(2)O6 octahedra,  a cornercorner with one Ni(1)O5 square pyramid, and  a faceface with one V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-61°. The Mg(1)-O(3) bond length is 2.10 Å. The Mg(1)-O(5) bond length is 2.07 Å. The Mg(1)-O(6) bond length is 2.03 Å. The Mg(1)-O(7) bond length is 2.12 Å. The Mg(1)-O(9) bond length is 2.03 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(10), one O(4), one O(5), one O(7), and one O(9) atom to form VO6 octahedra that share corners with three equivalent Ni(1)O5 square pyramids, edges with two equivalent V(2)O6 octahedra, and  a faceface with one Mg(1)O5 square pyramid. The V(1)-O(1) bond length is 1.90 Å. The V(1)-O(10) bond length is 1.88 Å. The V(1)-O(4) bond length is 1.98 Å. The V(1)-O(5) bond length is 2.07 Å. The V(1)-O(7) bond length is 2.21 Å. The V(1)-O(9) bond length is 1.88 Å. In the second V site, V(2) is bonded to one O(1), one O(10), one O(2), one O(4), one O(6), and one O(7) atom to form VO6 octahedra that share corners with two equivalent Mg(1)O5 square pyramids, corners with three equivalent Ni(1)O5 square pyramids, and edges with two equivalent V(1)O6 octahedra. The V(2)-O(1) bond length is 2.02 Å. The V(2)-O(10) bond length is 2.03 Å. The V(2)-O(2) bond length is 1.74 Å. The V(2)-O(4) bond length is 2.09 Å. The V(2)-O(6) bond length is 2.03 Å. The V(2)-O(7) bond length is 2.08 Å. Ni(1) is bonded to one O(1), one O(10), one O(2), one O(8), and one O(9) atom to form NiO5 square pyramids that share corners with three equivalent V(1)O6 octahedra, corners with three equivalent V(2)O6 octahedra, and  a cornercorner with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 47-56°. The Ni(1)-O(1) bond length is 2.03 Å. The Ni(1)-O(10) bond length is 2.00 Å. The Ni(1)-O(2) bond length is 2.19 Å. The Ni(1)-O(8) bond length is 2.19 Å. The Ni(1)-O(9) bond length is 2.14 Å. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a 5-coordinate geometry to one O(3), one O(6), one O(7), one O(8), and one O(9) atom. The Te(1)-O(3) bond length is 2.41 Å. The Te(1)-O(6) bond length is 2.00 Å. The Te(1)-O(7) bond length is 2.00 Å. The Te(1)-O(8) bond length is 1.92 Å. The Te(1)-O(9) bond length is 2.61 Å. In the second Te site, Te(2) is bonded in a 3-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and one O(8) atom. The Te(2)-O(2) bond length is 2.63 Å. The Te(2)-O(3) bond length is 1.93 Å. The Te(2)-O(4) bond length is 1.97 Å. The Te(2)-O(5) bond length is 1.95 Å. The Te(2)-O(8) bond length is 2.43 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one Ni(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one V(2), one Ni(1), and one Te(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Te(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one V(1), one V(2), and one Te(2) atom. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Mg(1), one V(1), and one Te(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one Te(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Mg(1), one V(1), one V(2), and one Te(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ni(1), one Te(1), and one Te(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one V(1), one Ni(1), and one Te(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one Ni(1) atom.