MgV3NiO8 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(6), one O(7), one O(8), and two equivalent O(3) atoms to form MgO5 square pyramids that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Mg(1)O5 square pyramids,  an edgeedge with one V(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent V(3)O6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(8) atoms to form distorted VO6 octahedra that share  a cornercorner with one V(3)O6 octahedra,  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent V(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra,  an edgeedge with one V(3)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Mg(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 6-31°. In the second V site, V(2) is bonded to one O(4), one O(5), one O(6), one O(7), and two equivalent O(1) atoms to form distorted VO6 octahedra that share  a cornercorner with one V(3)O6 octahedra,  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent V(2)O6 octahedra,  an edgeedge with one V(1)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent V(3)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 2-27°. In the third V site, V(3) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(7) atoms to form VO6 octahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, corners with two equivalent V(3)O6 octahedra,  an edgeedge with one V(1)O6 octahedra, edges with two equivalent V(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Mg(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 6-17°. Ni(1) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms to form distorted NiO6 octahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one Mg(1)O5 square pyramid,  an edgeedge with one V(2)O6 octahedra, edges with two equivalent V(1)O6 octahedra, edges with two equivalent V(3)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 2-31°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one V(3) and two equivalent V(2) atoms. In the second O site, O(2) is bonded to one V(1), one V(3), and two equivalent Ni(1) atoms to form distorted OV2Ni2 trigonal pyramids that share corners with two equivalent O(2)V2Ni2 trigonal pyramids and edges with two equivalent O(7)MgV3Ni square pyramids. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1), one V(1), and one V(3) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one V(1), one V(2), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one V(2), and one Ni(1) atom. In the seventh O site, O(7) is bonded to one Mg(1), one V(2), two equivalent V(3), and one Ni(1) atom to form distorted OMgV3Ni square pyramids that share corners with two equivalent O(7)MgV3Ni square pyramids and edges with two equivalent O(2)V2Ni2 trigonal pyramids. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent V(1), and one Ni(1) atom.
MgV3NiO8 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(6), one O(7), one O(8), and two equivalent O(3) atoms to form MgO5 square pyramids that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Mg(1)O5 square pyramids,  an edgeedge with one V(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent V(3)O6 octahedra. The corner-sharing octahedral tilt angles are 4°. The Mg(1)-O(6) bond length is 2.16 Å. The Mg(1)-O(7) bond length is 2.03 Å. The Mg(1)-O(8) bond length is 1.94 Å. Both Mg(1)-O(3) bond lengths are 2.01 Å. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(8) atoms to form distorted VO6 octahedra that share  a cornercorner with one V(3)O6 octahedra,  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent V(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra,  an edgeedge with one V(3)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Mg(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 6-31°. The V(1)-O(2) bond length is 2.06 Å. The V(1)-O(3) bond length is 2.00 Å. The V(1)-O(4) bond length is 2.15 Å. The V(1)-O(5) bond length is 1.77 Å. Both V(1)-O(8) bond lengths are 2.01 Å. In the second V site, V(2) is bonded to one O(4), one O(5), one O(6), one O(7), and two equivalent O(1) atoms to form distorted VO6 octahedra that share  a cornercorner with one V(3)O6 octahedra,  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent V(2)O6 octahedra,  an edgeedge with one V(1)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent V(3)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 2-27°. The V(2)-O(4) bond length is 1.94 Å. The V(2)-O(5) bond length is 2.11 Å. The V(2)-O(6) bond length is 1.73 Å. The V(2)-O(7) bond length is 2.07 Å. Both V(2)-O(1) bond lengths are 2.04 Å. In the third V site, V(3) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(7) atoms to form VO6 octahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, corners with two equivalent V(3)O6 octahedra,  an edgeedge with one V(1)O6 octahedra, edges with two equivalent V(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Mg(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 6-17°. The V(3)-O(1) bond length is 1.91 Å. The V(3)-O(2) bond length is 1.94 Å. The V(3)-O(3) bond length is 2.19 Å. The V(3)-O(4) bond length is 1.84 Å. Both V(3)-O(7) bond lengths are 2.00 Å. Ni(1) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms to form distorted NiO6 octahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one Mg(1)O5 square pyramid,  an edgeedge with one V(2)O6 octahedra, edges with two equivalent V(1)O6 octahedra, edges with two equivalent V(3)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 2-31°. The Ni(1)-O(5) bond length is 2.01 Å. The Ni(1)-O(6) bond length is 2.05 Å. The Ni(1)-O(7) bond length is 2.41 Å. The Ni(1)-O(8) bond length is 2.09 Å. Both Ni(1)-O(2) bond lengths are 2.05 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one V(3) and two equivalent V(2) atoms. In the second O site, O(2) is bonded to one V(1), one V(3), and two equivalent Ni(1) atoms to form distorted OV2Ni2 trigonal pyramids that share corners with two equivalent O(2)V2Ni2 trigonal pyramids and edges with two equivalent O(7)MgV3Ni square pyramids. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1), one V(1), and one V(3) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one V(1), one V(2), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one V(2), and one Ni(1) atom. In the seventh O site, O(7) is bonded to one Mg(1), one V(2), two equivalent V(3), and one Ni(1) atom to form distorted OMgV3Ni square pyramids that share corners with two equivalent O(7)MgV3Ni square pyramids and edges with two equivalent O(2)V2Ni2 trigonal pyramids. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent V(1), and one Ni(1) atom.