Ba2MgWNiO6 crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(1), and four equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with twelve equivalent Ba(1)O12 cuboctahedra, edges with three equivalent Ni(1)BaMgO3 trigonal bipyramids, and faces with four equivalent W(1)O6 octahedra. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one Ni(1), one O(4), two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Mg(1) is bonded in a distorted trigonal non-coplanar geometry to one Ni(1), one O(3), and two equivalent O(2) atoms. W(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form WO6 octahedra that share corners with three equivalent Ni(1)BaMgO3 trigonal bipyramids and faces with four equivalent Ba(1)O12 cuboctahedra. Ni(1) is bonded to one Ba(2), one Mg(1), one O(4), and two equivalent O(1) atoms to form distorted NiBaMgO3 trigonal bipyramids that share corners with three equivalent W(1)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(2), two equivalent Ba(1), one W(1), and one Ni(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Mg(1), and one W(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Mg(1), and one W(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(2), two equivalent Ba(1), one W(1), and one Ni(1) atom.
Ba2MgWNiO6 crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(1), and four equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with twelve equivalent Ba(1)O12 cuboctahedra, edges with three equivalent Ni(1)BaMgO3 trigonal bipyramids, and faces with four equivalent W(1)O6 octahedra. There is one shorter (2.99 Å) and one longer (3.28 Å) Ba(1)-O(3) bond length. Both Ba(1)-O(4) bond lengths are 3.01 Å. There are two shorter (3.01 Å) and two longer (3.02 Å) Ba(1)-O(1) bond lengths. There are two shorter (2.98 Å) and two longer (3.28 Å) Ba(1)-O(2) bond lengths. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one Ni(1), one O(4), two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. The Ba(2)-Ni(1) bond length is 2.73 Å. The Ba(2)-O(4) bond length is 2.82 Å. Both Ba(2)-O(1) bond lengths are 2.82 Å. Both Ba(2)-O(3) bond lengths are 3.03 Å. There are two shorter (3.03 Å) and two longer (3.04 Å) Ba(2)-O(2) bond lengths. Mg(1) is bonded in a distorted trigonal non-coplanar geometry to one Ni(1), one O(3), and two equivalent O(2) atoms. The Mg(1)-Ni(1) bond length is 2.35 Å. The Mg(1)-O(3) bond length is 1.95 Å. Both Mg(1)-O(2) bond lengths are 1.95 Å. W(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form WO6 octahedra that share corners with three equivalent Ni(1)BaMgO3 trigonal bipyramids and faces with four equivalent Ba(1)O12 cuboctahedra. The W(1)-O(3) bond length is 2.01 Å. The W(1)-O(4) bond length is 1.95 Å. Both W(1)-O(1) bond lengths are 1.95 Å. Both W(1)-O(2) bond lengths are 2.01 Å. Ni(1) is bonded to one Ba(2), one Mg(1), one O(4), and two equivalent O(1) atoms to form distorted NiBaMgO3 trigonal bipyramids that share corners with three equivalent W(1)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. The Ni(1)-O(4) bond length is 1.90 Å. Both Ni(1)-O(1) bond lengths are 1.91 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(2), two equivalent Ba(1), one W(1), and one Ni(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Mg(1), and one W(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Mg(1), and one W(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(2), two equivalent Ba(1), one W(1), and one Ni(1) atom.