MgNi(TeO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(4), and one O(7) atom. Ni(1) is bonded to one O(1), one O(11), one O(4), one O(7), one O(8), and one O(9) atom to form NiO6 octahedra that share corners with two equivalent Te(4)O6 octahedra,  an edgeedge with one Te(1)O6 octahedra, and edges with two equivalent Te(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-73°. There are four inequivalent Te sites. In the first Te site, Te(1) is bonded to one O(10), one O(11), one O(2), one O(3), one O(5), and one O(8) atom to form TeO6 octahedra that share corners with four equivalent Te(4)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-49°. In the second Te site, Te(2) is bonded to one O(1), one O(12), one O(4), one O(6), one O(7), and one O(9) atom to form TeO6 octahedra that share corners with two equivalent Te(4)O6 octahedra and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-43°. In the third Te site, Te(3) is bonded in a 4-coordinate geometry to one O(1), one O(12), one O(2), one O(4), and one O(9) atom. In the fourth Te site, Te(4) is bonded to one O(10), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form distorted TeO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Te(2)O6 octahedra, and corners with four equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-73°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Te(2), and one Te(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Te(1) and one Te(3) 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(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Ni(1), one Te(2), and one Te(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Te(1) and one Te(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Te(2) and one Te(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Te(2), and one Te(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ni(1), one Te(1), and one Te(4) atom. In the ninth O site, O(9) is bonded in a T-shaped geometry to one Ni(1), one Te(2), and one Te(3) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Te(1) and one Te(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one Te(1) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Mg(1), one Te(2), and one Te(3) atom.
MgNi(TeO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(4), and one O(7) atom. The Mg(1)-O(1) bond length is 2.05 Å. The Mg(1)-O(11) bond length is 2.04 Å. The Mg(1)-O(12) bond length is 2.43 Å. The Mg(1)-O(3) bond length is 1.98 Å. The Mg(1)-O(4) bond length is 2.33 Å. The Mg(1)-O(7) bond length is 2.18 Å. Ni(1) is bonded to one O(1), one O(11), one O(4), one O(7), one O(8), and one O(9) atom to form NiO6 octahedra that share corners with two equivalent Te(4)O6 octahedra,  an edgeedge with one Te(1)O6 octahedra, and edges with two equivalent Te(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-73°. The Ni(1)-O(1) bond length is 2.16 Å. The Ni(1)-O(11) bond length is 2.11 Å. The Ni(1)-O(4) bond length is 2.13 Å. The Ni(1)-O(7) bond length is 2.10 Å. The Ni(1)-O(8) bond length is 2.04 Å. The Ni(1)-O(9) bond length is 2.17 Å. There are four inequivalent Te sites. In the first Te site, Te(1) is bonded to one O(10), one O(11), one O(2), one O(3), one O(5), and one O(8) atom to form TeO6 octahedra that share corners with four equivalent Te(4)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-49°. The Te(1)-O(10) bond length is 2.00 Å. The Te(1)-O(11) bond length is 1.95 Å. The Te(1)-O(2) bond length is 2.01 Å. The Te(1)-O(3) bond length is 1.91 Å. The Te(1)-O(5) bond length is 1.96 Å. The Te(1)-O(8) bond length is 1.92 Å. In the second Te site, Te(2) is bonded to one O(1), one O(12), one O(4), one O(6), one O(7), and one O(9) atom to form TeO6 octahedra that share corners with two equivalent Te(4)O6 octahedra and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-43°. The Te(2)-O(1) bond length is 1.92 Å. The Te(2)-O(12) bond length is 2.07 Å. The Te(2)-O(4) bond length is 1.97 Å. The Te(2)-O(6) bond length is 1.94 Å. The Te(2)-O(7) bond length is 1.97 Å. The Te(2)-O(9) bond length is 1.95 Å. In the third Te site, Te(3) is bonded in a 4-coordinate geometry to one O(1), one O(12), one O(2), one O(4), and one O(9) atom. The Te(3)-O(1) bond length is 2.62 Å. The Te(3)-O(12) bond length is 1.97 Å. The Te(3)-O(2) bond length is 1.90 Å. The Te(3)-O(4) bond length is 2.31 Å. The Te(3)-O(9) bond length is 2.16 Å. In the fourth Te site, Te(4) is bonded to one O(10), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form distorted TeO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Te(2)O6 octahedra, and corners with four equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-73°. The Te(4)-O(10) bond length is 1.98 Å. The Te(4)-O(3) bond length is 2.46 Å. The Te(4)-O(5) bond length is 1.99 Å. The Te(4)-O(6) bond length is 2.00 Å. The Te(4)-O(7) bond length is 2.65 Å. The Te(4)-O(8) bond length is 2.44 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Te(2), and one Te(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Te(1) and one Te(3) 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(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Ni(1), one Te(2), and one Te(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Te(1) and one Te(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Te(2) and one Te(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Te(2), and one Te(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ni(1), one Te(1), and one Te(4) atom. In the ninth O site, O(9) is bonded in a T-shaped geometry to one Ni(1), one Te(2), and one Te(3) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Te(1) and one Te(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one Te(1) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Mg(1), one Te(2), and one Te(3) atom.