Na8Mg(NiO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(7) atom to form distorted NaO5 trigonal bipyramids that share  a cornercorner with one Ni(2)O4 tetrahedra, corners with two equivalent Ni(1)O4 tetrahedra,  a cornercorner with one Na(6)O4 trigonal pyramid, edges with two equivalent Na(3)O5 square pyramids, edges with two equivalent Na(4)O5 square pyramids,  an edgeedge with one Mg(1)O4 tetrahedra, and  an edgeedge with one Ni(2)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO5 square pyramids that share corners with three equivalent Na(4)O5 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Ni(1)O4 tetrahedra, corners with two equivalent Ni(2)O4 tetrahedra,  a cornercorner with one Na(6)O4 trigonal pyramid,  an edgeedge with one Na(4)O5 square pyramid,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. In the fourth Na site, Na(4) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO5 square pyramids that share corners with three equivalent Na(3)O5 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Ni(1)O4 tetrahedra,  a cornercorner with one Na(6)O4 trigonal pyramid,  an edgeedge with one Na(3)O5 square pyramid,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra,  an edgeedge with one Ni(2)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. In the fifth Na site, Na(5) is bonded in a 3-coordinate geometry to one O(4), one O(5), one O(6), and one O(8) atom. In the sixth Na site, Na(6) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(4)O5 square pyramid, corners with two equivalent Ni(1)O4 tetrahedra, corners with two equivalent Ni(2)O4 tetrahedra,  a cornercorner with one Na(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O4 tetrahedra. In the seventh Na site, Na(7) is bonded in a distorted see-saw-like geometry to one O(2), one O(5), one O(7), and one O(8) atom. In the eighth Na site, Na(8) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(7) atom. Mg(1) is bonded to one O(3), one O(4), one O(6), and one O(8) atom to form MgO4 tetrahedra that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(4)O5 square pyramid,  a cornercorner with one Ni(2)O4 tetrahedra, corners with three equivalent Ni(1)O4 tetrahedra,  an edgeedge with one Na(3)O5 square pyramid,  an edgeedge with one Na(4)O5 square pyramid,  an edgeedge with one Na(1)O5 trigonal bipyramid, and  an edgeedge with one Na(6)O4 trigonal pyramid. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form NiO4 tetrahedra that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(4)O5 square pyramid, corners with three equivalent Mg(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, corners with two equivalent Na(6)O4 trigonal pyramids,  an edgeedge with one Na(3)O5 square pyramid, and  an edgeedge with one Na(4)O5 square pyramid. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form NiO4 tetrahedra that share corners with two equivalent Na(3)O5 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Na(1)O5 trigonal bipyramid, corners with two equivalent Na(6)O4 trigonal pyramids,  an edgeedge with one Na(4)O5 square pyramid, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in an octahedral geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(8), and one Ni(2) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(7), one Na(8), and one Ni(2) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), one Mg(1), and one Ni(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(5), one Na(6), one Na(7), one Na(8), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Na(3), one Na(4), one Na(5), one Na(6), one Mg(1), and one Ni(1) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(6), one Na(7), one Na(8), and one Ni(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Na(5), one Na(6), one Na(7), one Mg(1), and one Ni(2) atom.
Na8Mg(NiO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(7) atom to form distorted NaO5 trigonal bipyramids that share  a cornercorner with one Ni(2)O4 tetrahedra, corners with two equivalent Ni(1)O4 tetrahedra,  a cornercorner with one Na(6)O4 trigonal pyramid, edges with two equivalent Na(3)O5 square pyramids, edges with two equivalent Na(4)O5 square pyramids,  an edgeedge with one Mg(1)O4 tetrahedra, and  an edgeedge with one Ni(2)O4 tetrahedra. The Na(1)-O(1) bond length is 2.47 Å. The Na(1)-O(2) bond length is 2.49 Å. The Na(1)-O(3) bond length is 2.33 Å. The Na(1)-O(4) bond length is 2.43 Å. The Na(1)-O(7) bond length is 2.37 Å. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. The Na(2)-O(1) bond length is 2.44 Å. The Na(2)-O(2) bond length is 2.53 Å. The Na(2)-O(3) bond length is 2.45 Å. The Na(2)-O(4) bond length is 2.80 Å. The Na(2)-O(7) bond length is 2.34 Å. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO5 square pyramids that share corners with three equivalent Na(4)O5 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Ni(1)O4 tetrahedra, corners with two equivalent Ni(2)O4 tetrahedra,  a cornercorner with one Na(6)O4 trigonal pyramid,  an edgeedge with one Na(4)O5 square pyramid,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. The Na(3)-O(1) bond length is 2.30 Å. The Na(3)-O(2) bond length is 2.66 Å. The Na(3)-O(3) bond length is 2.46 Å. The Na(3)-O(4) bond length is 2.52 Å. The Na(3)-O(6) bond length is 2.69 Å. In the fourth Na site, Na(4) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO5 square pyramids that share corners with three equivalent Na(3)O5 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Ni(1)O4 tetrahedra,  a cornercorner with one Na(6)O4 trigonal pyramid,  an edgeedge with one Na(3)O5 square pyramid,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra,  an edgeedge with one Ni(2)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. The Na(4)-O(1) bond length is 2.27 Å. The Na(4)-O(2) bond length is 2.41 Å. The Na(4)-O(3) bond length is 2.58 Å. The Na(4)-O(4) bond length is 2.45 Å. The Na(4)-O(6) bond length is 2.49 Å. In the fifth Na site, Na(5) is bonded in a 3-coordinate geometry to one O(4), one O(5), one O(6), and one O(8) atom. The Na(5)-O(4) bond length is 2.70 Å. The Na(5)-O(5) bond length is 2.32 Å. The Na(5)-O(6) bond length is 2.32 Å. The Na(5)-O(8) bond length is 2.28 Å. In the sixth Na site, Na(6) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(4)O5 square pyramid, corners with two equivalent Ni(1)O4 tetrahedra, corners with two equivalent Ni(2)O4 tetrahedra,  a cornercorner with one Na(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O4 tetrahedra. The Na(6)-O(5) bond length is 2.33 Å. The Na(6)-O(6) bond length is 2.38 Å. The Na(6)-O(7) bond length is 2.36 Å. The Na(6)-O(8) bond length is 2.44 Å. In the seventh Na site, Na(7) is bonded in a distorted see-saw-like geometry to one O(2), one O(5), one O(7), and one O(8) atom. The Na(7)-O(2) bond length is 2.38 Å. The Na(7)-O(5) bond length is 2.24 Å. The Na(7)-O(7) bond length is 2.29 Å. The Na(7)-O(8) bond length is 2.24 Å. In the eighth Na site, Na(8) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(7) atom. The Na(8)-O(1) bond length is 2.22 Å. The Na(8)-O(2) bond length is 2.46 Å. The Na(8)-O(5) bond length is 2.39 Å. The Na(8)-O(7) bond length is 2.31 Å. Mg(1) is bonded to one O(3), one O(4), one O(6), and one O(8) atom to form MgO4 tetrahedra that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(4)O5 square pyramid,  a cornercorner with one Ni(2)O4 tetrahedra, corners with three equivalent Ni(1)O4 tetrahedra,  an edgeedge with one Na(3)O5 square pyramid,  an edgeedge with one Na(4)O5 square pyramid,  an edgeedge with one Na(1)O5 trigonal bipyramid, and  an edgeedge with one Na(6)O4 trigonal pyramid. The Mg(1)-O(3) bond length is 2.04 Å. The Mg(1)-O(4) bond length is 2.09 Å. The Mg(1)-O(6) bond length is 2.00 Å. The Mg(1)-O(8) bond length is 2.03 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form NiO4 tetrahedra that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(4)O5 square pyramid, corners with three equivalent Mg(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, corners with two equivalent Na(6)O4 trigonal pyramids,  an edgeedge with one Na(3)O5 square pyramid, and  an edgeedge with one Na(4)O5 square pyramid. The Ni(1)-O(3) bond length is 1.91 Å. The Ni(1)-O(4) bond length is 1.96 Å. The Ni(1)-O(5) bond length is 1.79 Å. The Ni(1)-O(6) bond length is 1.94 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form NiO4 tetrahedra that share corners with two equivalent Na(3)O5 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Na(1)O5 trigonal bipyramid, corners with two equivalent Na(6)O4 trigonal pyramids,  an edgeedge with one Na(4)O5 square pyramid, and  an edgeedge with one Na(1)O5 trigonal bipyramid. The Ni(2)-O(1) bond length is 1.86 Å. The Ni(2)-O(2) bond length is 1.90 Å. The Ni(2)-O(7) bond length is 1.83 Å. The Ni(2)-O(8) bond length is 1.94 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in an octahedral geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(8), and one Ni(2) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(7), one Na(8), and one Ni(2) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), one Mg(1), and one Ni(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(5), one Na(6), one Na(7), one Na(8), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Na(3), one Na(4), one Na(5), one Na(6), one Mg(1), and one Ni(1) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(6), one Na(7), one Na(8), and one Ni(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Na(5), one Na(6), one Na(7), one Mg(1), and one Ni(2) atom.