MgTl4(NiO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(7), one O(8), and one O(9) atom. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(10), one O(2), one O(5), one O(6), and one O(7) atom to form distorted corner-sharing NiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 24-52°. In the second Ni site, Ni(2) is bonded to one O(1), one O(12), one O(3), one O(4), one O(6), and one O(8) atom to form corner-sharing NiO6 octahedra. In the third Ni site, Ni(3) is bonded to one O(1), one O(11), one O(12), one O(3), and one O(4) atom to form corner-sharing NiO5 square pyramids. The corner-sharing octahedral tilt angles range from 27-45°. In the fourth Ni site, Ni(4) is bonded to one O(10), one O(11), one O(2), one O(5), one O(7), and one O(9) atom to form distorted corner-sharing NiO6 octahedra. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(2), one O(4), one O(5), and one O(6) atom. In the second Tl site, Tl(2) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(3), one O(4), one O(8), and one O(9) atom. In the third Tl site, Tl(3) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(2), one O(7), one O(8), and one O(9) atom. In the fourth Tl site, Tl(4) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(3), one O(4), one O(5), and one O(6) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ni(2), one Ni(3), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(2)MgTl2Ni2 square pyramid,  a cornercorner with one O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(8)MgTl2Ni trigonal pyramid, corners with two equivalent O(12)Tl2Ni2 trigonal pyramids,  an edgeedge with one O(11)Tl2Ni2 tetrahedra, and edges with two equivalent O(4)Tl3Ni2 trigonal bipyramids. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), one Ni(4), one Tl(1), and one Tl(3) atom to form distorted OMgTl2Ni2 square pyramids that share  a cornercorner with one O(1)Tl2Ni2 tetrahedra, corners with two equivalent O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)Tl3Ni2 trigonal bipyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid, corners with two equivalent O(8)MgTl2Ni trigonal pyramids, and  a faceface with one O(9)MgTl2Ni trigonal pyramid. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ni(2), one Ni(3), one Tl(2), and one Tl(4) atom. In the fourth O site, O(4) is bonded to one Ni(2), one Ni(3), one Tl(1), one Tl(2), and one Tl(4) atom to form distorted OTl3Ni2 trigonal bipyramids that share  a cornercorner with one O(2)MgTl2Ni2 square pyramid, corners with three equivalent O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)MgTl2Ni trigonal pyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid, edges with two equivalent O(1)Tl2Ni2 tetrahedra,  an edgeedge with one O(8)MgTl2Ni trigonal pyramid, and  an edgeedge with one O(12)Tl2Ni2 trigonal pyramid. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Ni(1), one Ni(4), one Tl(1), and one Tl(4) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Ni(1), one Ni(2), one Tl(1), and one Tl(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Ni(4), and one Tl(3) atom. In the eighth O site, O(8) is bonded to one Mg(1), one Ni(2), one Tl(2), and one Tl(3) atom to form distorted OMgTl2Ni trigonal pyramids that share corners with two equivalent O(2)MgTl2Ni2 square pyramids,  a cornercorner with one O(1)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)MgTl2Ni trigonal pyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid,  an edgeedge with one O(4)Tl3Ni2 trigonal bipyramid,  an edgeedge with one O(9)MgTl2Ni trigonal pyramid, and  an edgeedge with one O(12)Tl2Ni2 trigonal pyramid. In the ninth O site, O(9) is bonded to one Mg(1), one Ni(4), one Tl(2), and one Tl(3) atom to form distorted OMgTl2Ni trigonal pyramids that share  a cornercorner with one O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)Tl3Ni2 trigonal bipyramid,  a cornercorner with one O(8)MgTl2Ni trigonal pyramid, corners with two equivalent O(12)Tl2Ni2 trigonal pyramids,  an edgeedge with one O(8)MgTl2Ni trigonal pyramid, and  a faceface with one O(2)MgTl2Ni2 square pyramid. In the tenth O site, O(10) is bonded in a distorted rectangular see-saw-like geometry to one Ni(1), one Ni(4), one Tl(2), and one Tl(3) atom. In the eleventh O site, O(11) is bonded to one Ni(3), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 tetrahedra that share corners with two equivalent O(2)MgTl2Ni2 square pyramids,  a cornercorner with one O(1)Tl2Ni2 tetrahedra, corners with three equivalent O(4)Tl3Ni2 trigonal bipyramids,  a cornercorner with one O(9)MgTl2Ni trigonal pyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid, and  an edgeedge with one O(1)Tl2Ni2 tetrahedra. In the twelfth O site, O(12) is bonded to one Ni(2), one Ni(3), one Tl(2), and one Tl(3) atom to form OTl2Ni2 trigonal pyramids that share  a cornercorner with one O(2)MgTl2Ni2 square pyramid,  a cornercorner with one O(11)Tl2Ni2 tetrahedra, corners with two equivalent O(1)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)Tl3Ni2 trigonal bipyramid,  a cornercorner with one O(8)MgTl2Ni trigonal pyramid, corners with two equivalent O(9)MgTl2Ni trigonal pyramids,  an edgeedge with one O(4)Tl3Ni2 trigonal bipyramid, and  an edgeedge with one O(8)MgTl2Ni trigonal pyramid.
MgTl4(NiO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(7), one O(8), and one O(9) atom. The Mg(1)-O(2) bond length is 2.17 Å. The Mg(1)-O(5) bond length is 2.11 Å. The Mg(1)-O(7) bond length is 1.99 Å. The Mg(1)-O(8) bond length is 2.00 Å. The Mg(1)-O(9) bond length is 2.06 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(10), one O(2), one O(5), one O(6), and one O(7) atom to form distorted corner-sharing NiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 24-52°. The Ni(1)-O(10) bond length is 1.94 Å. The Ni(1)-O(2) bond length is 1.96 Å. The Ni(1)-O(5) bond length is 2.10 Å. The Ni(1)-O(6) bond length is 2.02 Å. The Ni(1)-O(7) bond length is 1.91 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(12), one O(3), one O(4), one O(6), and one O(8) atom to form corner-sharing NiO6 octahedra. The Ni(2)-O(1) bond length is 2.03 Å. The Ni(2)-O(12) bond length is 2.16 Å. The Ni(2)-O(3) bond length is 2.06 Å. The Ni(2)-O(4) bond length is 2.41 Å. The Ni(2)-O(6) bond length is 2.07 Å. The Ni(2)-O(8) bond length is 2.06 Å. In the third Ni site, Ni(3) is bonded to one O(1), one O(11), one O(12), one O(3), and one O(4) atom to form corner-sharing NiO5 square pyramids. The corner-sharing octahedral tilt angles range from 27-45°. The Ni(3)-O(1) bond length is 1.92 Å. The Ni(3)-O(11) bond length is 2.08 Å. The Ni(3)-O(12) bond length is 1.96 Å. The Ni(3)-O(3) bond length is 1.92 Å. The Ni(3)-O(4) bond length is 1.96 Å. In the fourth Ni site, Ni(4) is bonded to one O(10), one O(11), one O(2), one O(5), one O(7), and one O(9) atom to form distorted corner-sharing NiO6 octahedra. The Ni(4)-O(10) bond length is 1.99 Å. The Ni(4)-O(11) bond length is 2.03 Å. The Ni(4)-O(2) bond length is 2.10 Å. The Ni(4)-O(5) bond length is 2.22 Å. The Ni(4)-O(7) bond length is 2.21 Å. The Ni(4)-O(9) bond length is 2.10 Å. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(2), one O(4), one O(5), and one O(6) atom. The Tl(1)-O(1) bond length is 2.26 Å. The Tl(1)-O(11) bond length is 2.19 Å. The Tl(1)-O(2) bond length is 2.42 Å. The Tl(1)-O(4) bond length is 2.32 Å. The Tl(1)-O(5) bond length is 2.71 Å. The Tl(1)-O(6) bond length is 2.35 Å. In the second Tl site, Tl(2) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(3), one O(4), one O(8), and one O(9) atom. The Tl(2)-O(10) bond length is 2.49 Å. The Tl(2)-O(12) bond length is 2.27 Å. The Tl(2)-O(3) bond length is 2.20 Å. The Tl(2)-O(4) bond length is 2.39 Å. The Tl(2)-O(8) bond length is 2.19 Å. The Tl(2)-O(9) bond length is 2.32 Å. In the third Tl site, Tl(3) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(2), one O(7), one O(8), and one O(9) atom. The Tl(3)-O(10) bond length is 2.24 Å. The Tl(3)-O(12) bond length is 2.27 Å. The Tl(3)-O(2) bond length is 2.47 Å. The Tl(3)-O(7) bond length is 2.43 Å. The Tl(3)-O(8) bond length is 2.56 Å. The Tl(3)-O(9) bond length is 2.17 Å. In the fourth Tl site, Tl(4) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(3), one O(4), one O(5), and one O(6) atom. The Tl(4)-O(1) bond length is 2.36 Å. The Tl(4)-O(11) bond length is 2.35 Å. The Tl(4)-O(3) bond length is 2.54 Å. The Tl(4)-O(4) bond length is 2.31 Å. The Tl(4)-O(5) bond length is 2.28 Å. The Tl(4)-O(6) bond length is 2.25 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ni(2), one Ni(3), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(2)MgTl2Ni2 square pyramid,  a cornercorner with one O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(8)MgTl2Ni trigonal pyramid, corners with two equivalent O(12)Tl2Ni2 trigonal pyramids,  an edgeedge with one O(11)Tl2Ni2 tetrahedra, and edges with two equivalent O(4)Tl3Ni2 trigonal bipyramids. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), one Ni(4), one Tl(1), and one Tl(3) atom to form distorted OMgTl2Ni2 square pyramids that share  a cornercorner with one O(1)Tl2Ni2 tetrahedra, corners with two equivalent O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)Tl3Ni2 trigonal bipyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid, corners with two equivalent O(8)MgTl2Ni trigonal pyramids, and  a faceface with one O(9)MgTl2Ni trigonal pyramid. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ni(2), one Ni(3), one Tl(2), and one Tl(4) atom. In the fourth O site, O(4) is bonded to one Ni(2), one Ni(3), one Tl(1), one Tl(2), and one Tl(4) atom to form distorted OTl3Ni2 trigonal bipyramids that share  a cornercorner with one O(2)MgTl2Ni2 square pyramid, corners with three equivalent O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)MgTl2Ni trigonal pyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid, edges with two equivalent O(1)Tl2Ni2 tetrahedra,  an edgeedge with one O(8)MgTl2Ni trigonal pyramid, and  an edgeedge with one O(12)Tl2Ni2 trigonal pyramid. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Ni(1), one Ni(4), one Tl(1), and one Tl(4) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Ni(1), one Ni(2), one Tl(1), and one Tl(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Ni(4), and one Tl(3) atom. In the eighth O site, O(8) is bonded to one Mg(1), one Ni(2), one Tl(2), and one Tl(3) atom to form distorted OMgTl2Ni trigonal pyramids that share corners with two equivalent O(2)MgTl2Ni2 square pyramids,  a cornercorner with one O(1)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)MgTl2Ni trigonal pyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid,  an edgeedge with one O(4)Tl3Ni2 trigonal bipyramid,  an edgeedge with one O(9)MgTl2Ni trigonal pyramid, and  an edgeedge with one O(12)Tl2Ni2 trigonal pyramid. In the ninth O site, O(9) is bonded to one Mg(1), one Ni(4), one Tl(2), and one Tl(3) atom to form distorted OMgTl2Ni trigonal pyramids that share  a cornercorner with one O(11)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)Tl3Ni2 trigonal bipyramid,  a cornercorner with one O(8)MgTl2Ni trigonal pyramid, corners with two equivalent O(12)Tl2Ni2 trigonal pyramids,  an edgeedge with one O(8)MgTl2Ni trigonal pyramid, and  a faceface with one O(2)MgTl2Ni2 square pyramid. In the tenth O site, O(10) is bonded in a distorted rectangular see-saw-like geometry to one Ni(1), one Ni(4), one Tl(2), and one Tl(3) atom. In the eleventh O site, O(11) is bonded to one Ni(3), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 tetrahedra that share corners with two equivalent O(2)MgTl2Ni2 square pyramids,  a cornercorner with one O(1)Tl2Ni2 tetrahedra, corners with three equivalent O(4)Tl3Ni2 trigonal bipyramids,  a cornercorner with one O(9)MgTl2Ni trigonal pyramid,  a cornercorner with one O(12)Tl2Ni2 trigonal pyramid, and  an edgeedge with one O(1)Tl2Ni2 tetrahedra. In the twelfth O site, O(12) is bonded to one Ni(2), one Ni(3), one Tl(2), and one Tl(3) atom to form OTl2Ni2 trigonal pyramids that share  a cornercorner with one O(2)MgTl2Ni2 square pyramid,  a cornercorner with one O(11)Tl2Ni2 tetrahedra, corners with two equivalent O(1)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)Tl3Ni2 trigonal bipyramid,  a cornercorner with one O(8)MgTl2Ni trigonal pyramid, corners with two equivalent O(9)MgTl2Ni trigonal pyramids,  an edgeedge with one O(4)Tl3Ni2 trigonal bipyramid, and  an edgeedge with one O(8)MgTl2Ni trigonal pyramid.