MgTl4(NiO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(11), one O(12), one O(4), and one O(6) atom to form MgO5 trigonal bipyramids that share  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one Tl(4)O6 octahedra,  a cornercorner with one Ni(3)O5 trigonal bipyramid,  an edgeedge with one Tl(4)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and  an edgeedge with one Ni(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-57°. 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(7), and one O(8) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Tl(4)O6 octahedra, corners with four equivalent Ni(4)O6 octahedra, and  an edgeedge with one Tl(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-81°. 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 NiO6 octahedra that share corners with two equivalent Tl(4)O6 octahedra,  a cornercorner with one Ni(1)O5 trigonal bipyramid, corners with four equivalent Ni(3)O5 trigonal bipyramids, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 41-43°. In the third Ni site, Ni(3) is bonded to one O(1), one O(12), one O(3), one O(4), and one O(9) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one Tl(4)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 22-84°. 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 NiO6 octahedra that share  a cornercorner with one Tl(4)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid,  a cornercorner with one Ni(3)O5 trigonal bipyramid, corners with four equivalent Ni(1)O5 trigonal bipyramids, and  a faceface with one Tl(4)O6 octahedra. The corner-sharing octahedral tilt angles are 66°. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 6-coordinate geometry to one O(10), 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(7), one O(8), and one O(9) atom. In the third Tl site, Tl(3) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(3), one O(8), and one O(9) atom. In the fourth Tl site, Tl(4) is bonded to one O(1), one O(11), one O(2), one O(5), one O(6), and one O(7) atom to form distorted TlO6 octahedra that share  a cornercorner with one Ni(4)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid,  a cornercorner with one Ni(1)O5 trigonal bipyramid,  a cornercorner with one Ni(3)O5 trigonal bipyramid,  an edgeedge with one Mg(1)O5 trigonal bipyramid,  an edgeedge with one Ni(1)O5 trigonal bipyramid, and  a faceface with one Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-66°. 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(2), one Ni(3), and one Tl(4) atom. In the second O site, O(2) is bonded to one Ni(1), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 trigonal pyramids that share  a cornercorner with one O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)Tl2Ni2 tetrahedra,  a cornercorner with one O(11)MgTl2Ni trigonal pyramid,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid, edges with two equivalent O(5)Tl2Ni2 tetrahedra, and  an edgeedge with one O(11)MgTl2Ni trigonal pyramid. In the third O site, O(3) is bonded to one Ni(2), one Ni(3), one Tl(2), and one Tl(3) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(8)Tl2Ni2 tetrahedra, corners with three equivalent O(9)Tl2Ni2 tetrahedra, corners with two equivalent O(4)MgTlNi2 trigonal pyramids, edges with two equivalent O(12)MgTl2Ni2 square pyramids, and  an edgeedge with one O(8)Tl2Ni2 tetrahedra. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(2), one Ni(3), and one Tl(1) atom to form distorted OMgTlNi2 trigonal pyramids that share  a cornercorner with one O(12)MgTl2Ni2 square pyramid,  a cornercorner with one O(5)Tl2Ni2 tetrahedra,  a cornercorner with one O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)Tl2Ni2 tetrahedra, corners with two equivalent O(3)Tl2Ni2 tetrahedra,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, corners with two equivalent O(11)MgTl2Ni trigonal pyramids, and  an edgeedge with one O(12)MgTl2Ni2 square pyramid. In the fifth O site, O(5) is bonded to one Ni(1), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid, corners with three equivalent O(11)MgTl2Ni trigonal pyramids, and edges with two equivalent O(2)Tl2Ni2 trigonal pyramids. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(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 Ni(1), one Ni(4), one Tl(2), and one Tl(4) atom. In the eighth O site, O(8) is bonded to one Ni(1), one Ni(2), one Tl(2), and one Tl(3) atom to form distorted OTl2Ni2 tetrahedra that share corners with three equivalent O(12)MgTl2Ni2 square pyramids,  a cornercorner with one O(3)Tl2Ni2 tetrahedra,  a cornercorner with one O(5)Tl2Ni2 tetrahedra, corners with two equivalent O(9)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, and  an edgeedge with one O(3)Tl2Ni2 tetrahedra. In the ninth O site, O(9) is bonded to one Ni(3), one Ni(4), one Tl(2), and one Tl(3) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(12)MgTl2Ni2 square pyramid,  a cornercorner with one O(5)Tl2Ni2 tetrahedra, corners with two equivalent O(8)Tl2Ni2 tetrahedra, corners with three equivalent O(3)Tl2Ni2 tetrahedra,  a cornercorner with one O(11)MgTl2Ni trigonal pyramid,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, and  an edgeedge with one O(12)MgTl2Ni2 square pyramid. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Ni(1), one Ni(4), one Tl(1), one Tl(2), and one Tl(3) atom. In the eleventh O site, O(11) is bonded to one Mg(1), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OMgTl2Ni trigonal pyramids that share  a cornercorner with one O(12)MgTl2Ni2 square pyramid,  a cornercorner with one O(9)Tl2Ni2 tetrahedra, corners with three equivalent O(5)Tl2Ni2 tetrahedra,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, corners with two equivalent O(4)MgTlNi2 trigonal pyramids, and  an edgeedge with one O(2)Tl2Ni2 trigonal pyramid. In the twelfth O site, O(12) is bonded to one Mg(1), one Ni(2), one Ni(3), one Tl(2), and one Tl(3) atom to form distorted OMgTl2Ni2 square pyramids that share  a cornercorner with one O(9)Tl2Ni2 tetrahedra, corners with three equivalent O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(11)MgTl2Ni trigonal pyramid,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid,  an edgeedge with one O(9)Tl2Ni2 tetrahedra, edges with two equivalent O(3)Tl2Ni2 tetrahedra, and  an edgeedge with one O(4)MgTlNi2 trigonal pyramid.
MgTl4(NiO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(11), one O(12), one O(4), and one O(6) atom to form MgO5 trigonal bipyramids that share  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one Tl(4)O6 octahedra,  a cornercorner with one Ni(3)O5 trigonal bipyramid,  an edgeedge with one Tl(4)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and  an edgeedge with one Ni(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-57°. The Mg(1)-O(1) bond length is 2.08 Å. The Mg(1)-O(11) bond length is 2.08 Å. The Mg(1)-O(12) bond length is 1.99 Å. The Mg(1)-O(4) bond length is 2.01 Å. The Mg(1)-O(6) 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(7), and one O(8) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Tl(4)O6 octahedra, corners with four equivalent Ni(4)O6 octahedra, and  an edgeedge with one Tl(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-81°. The Ni(1)-O(10) bond length is 1.98 Å. The Ni(1)-O(2) bond length is 1.97 Å. The Ni(1)-O(5) bond length is 1.95 Å. The Ni(1)-O(7) bond length is 1.95 Å. The Ni(1)-O(8) bond length is 2.07 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 NiO6 octahedra that share corners with two equivalent Tl(4)O6 octahedra,  a cornercorner with one Ni(1)O5 trigonal bipyramid, corners with four equivalent Ni(3)O5 trigonal bipyramids, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 41-43°. The Ni(2)-O(1) bond length is 2.18 Å. The Ni(2)-O(12) bond length is 2.28 Å. The Ni(2)-O(3) bond length is 2.07 Å. The Ni(2)-O(4) bond length is 2.10 Å. The Ni(2)-O(6) bond length is 2.06 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(12), one O(3), one O(4), and one O(9) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one Tl(4)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 22-84°. The Ni(3)-O(1) bond length is 1.93 Å. The Ni(3)-O(12) bond length is 2.08 Å. The Ni(3)-O(3) bond length is 1.90 Å. The Ni(3)-O(4) bond length is 2.03 Å. The Ni(3)-O(9) bond length is 2.05 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 NiO6 octahedra that share  a cornercorner with one Tl(4)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid,  a cornercorner with one Ni(3)O5 trigonal bipyramid, corners with four equivalent Ni(1)O5 trigonal bipyramids, and  a faceface with one Tl(4)O6 octahedra. The corner-sharing octahedral tilt angles are 66°. The Ni(4)-O(10) bond length is 2.13 Å. The Ni(4)-O(11) bond length is 2.08 Å. The Ni(4)-O(2) bond length is 2.20 Å. The Ni(4)-O(5) bond length is 2.06 Å. The Ni(4)-O(7) bond length is 2.09 Å. The Ni(4)-O(9) bond length is 2.03 Å. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(5), and one O(6) atom. The Tl(1)-O(10) bond length is 2.71 Å. The Tl(1)-O(11) bond length is 2.26 Å. The Tl(1)-O(2) bond length is 2.18 Å. The Tl(1)-O(4) bond length is 2.30 Å. The Tl(1)-O(5) bond length is 2.44 Å. The Tl(1)-O(6) bond length is 2.23 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(7), one O(8), and one O(9) atom. The Tl(2)-O(10) bond length is 2.50 Å. The Tl(2)-O(12) bond length is 2.23 Å. The Tl(2)-O(3) bond length is 2.50 Å. The Tl(2)-O(7) bond length is 2.24 Å. The Tl(2)-O(8) bond length is 2.16 Å. The Tl(2)-O(9) bond length is 2.46 Å. In the third Tl site, Tl(3) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(3), one O(8), and one O(9) atom. The Tl(3)-O(10) bond length is 2.25 Å. The Tl(3)-O(12) bond length is 2.50 Å. The Tl(3)-O(3) bond length is 2.18 Å. The Tl(3)-O(8) bond length is 2.47 Å. The Tl(3)-O(9) bond length is 2.15 Å. In the fourth Tl site, Tl(4) is bonded to one O(1), one O(11), one O(2), one O(5), one O(6), and one O(7) atom to form distorted TlO6 octahedra that share  a cornercorner with one Ni(4)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid,  a cornercorner with one Ni(1)O5 trigonal bipyramid,  a cornercorner with one Ni(3)O5 trigonal bipyramid,  an edgeedge with one Mg(1)O5 trigonal bipyramid,  an edgeedge with one Ni(1)O5 trigonal bipyramid, and  a faceface with one Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-66°. The Tl(4)-O(1) bond length is 2.44 Å. The Tl(4)-O(11) bond length is 2.19 Å. The Tl(4)-O(2) bond length is 2.33 Å. The Tl(4)-O(5) bond length is 2.26 Å. The Tl(4)-O(6) bond length is 2.28 Å. The Tl(4)-O(7) bond length is 2.42 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(2), one Ni(3), and one Tl(4) atom. In the second O site, O(2) is bonded to one Ni(1), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 trigonal pyramids that share  a cornercorner with one O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)Tl2Ni2 tetrahedra,  a cornercorner with one O(11)MgTl2Ni trigonal pyramid,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid, edges with two equivalent O(5)Tl2Ni2 tetrahedra, and  an edgeedge with one O(11)MgTl2Ni trigonal pyramid. In the third O site, O(3) is bonded to one Ni(2), one Ni(3), one Tl(2), and one Tl(3) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(8)Tl2Ni2 tetrahedra, corners with three equivalent O(9)Tl2Ni2 tetrahedra, corners with two equivalent O(4)MgTlNi2 trigonal pyramids, edges with two equivalent O(12)MgTl2Ni2 square pyramids, and  an edgeedge with one O(8)Tl2Ni2 tetrahedra. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(2), one Ni(3), and one Tl(1) atom to form distorted OMgTlNi2 trigonal pyramids that share  a cornercorner with one O(12)MgTl2Ni2 square pyramid,  a cornercorner with one O(5)Tl2Ni2 tetrahedra,  a cornercorner with one O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)Tl2Ni2 tetrahedra, corners with two equivalent O(3)Tl2Ni2 tetrahedra,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, corners with two equivalent O(11)MgTl2Ni trigonal pyramids, and  an edgeedge with one O(12)MgTl2Ni2 square pyramid. In the fifth O site, O(5) is bonded to one Ni(1), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(9)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid, corners with three equivalent O(11)MgTl2Ni trigonal pyramids, and edges with two equivalent O(2)Tl2Ni2 trigonal pyramids. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(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 Ni(1), one Ni(4), one Tl(2), and one Tl(4) atom. In the eighth O site, O(8) is bonded to one Ni(1), one Ni(2), one Tl(2), and one Tl(3) atom to form distorted OTl2Ni2 tetrahedra that share corners with three equivalent O(12)MgTl2Ni2 square pyramids,  a cornercorner with one O(3)Tl2Ni2 tetrahedra,  a cornercorner with one O(5)Tl2Ni2 tetrahedra, corners with two equivalent O(9)Tl2Ni2 tetrahedra,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, and  an edgeedge with one O(3)Tl2Ni2 tetrahedra. In the ninth O site, O(9) is bonded to one Ni(3), one Ni(4), one Tl(2), and one Tl(3) atom to form distorted OTl2Ni2 tetrahedra that share  a cornercorner with one O(12)MgTl2Ni2 square pyramid,  a cornercorner with one O(5)Tl2Ni2 tetrahedra, corners with two equivalent O(8)Tl2Ni2 tetrahedra, corners with three equivalent O(3)Tl2Ni2 tetrahedra,  a cornercorner with one O(11)MgTl2Ni trigonal pyramid,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, and  an edgeedge with one O(12)MgTl2Ni2 square pyramid. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Ni(1), one Ni(4), one Tl(1), one Tl(2), and one Tl(3) atom. In the eleventh O site, O(11) is bonded to one Mg(1), one Ni(4), one Tl(1), and one Tl(4) atom to form distorted OMgTl2Ni trigonal pyramids that share  a cornercorner with one O(12)MgTl2Ni2 square pyramid,  a cornercorner with one O(9)Tl2Ni2 tetrahedra, corners with three equivalent O(5)Tl2Ni2 tetrahedra,  a cornercorner with one O(2)Tl2Ni2 trigonal pyramid, corners with two equivalent O(4)MgTlNi2 trigonal pyramids, and  an edgeedge with one O(2)Tl2Ni2 trigonal pyramid. In the twelfth O site, O(12) is bonded to one Mg(1), one Ni(2), one Ni(3), one Tl(2), and one Tl(3) atom to form distorted OMgTl2Ni2 square pyramids that share  a cornercorner with one O(9)Tl2Ni2 tetrahedra, corners with three equivalent O(8)Tl2Ni2 tetrahedra,  a cornercorner with one O(11)MgTl2Ni trigonal pyramid,  a cornercorner with one O(4)MgTlNi2 trigonal pyramid,  an edgeedge with one O(9)Tl2Ni2 tetrahedra, edges with two equivalent O(3)Tl2Ni2 tetrahedra, and  an edgeedge with one O(4)MgTlNi2 trigonal pyramid.