Mn3NiCu2O8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. Mn(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Cu(1)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. Ni(1) is bonded to six equivalent O(2) atoms to form NiO6 octahedra that share corners with six equivalent Cu(1)O4 tetrahedra and edges with six equivalent Mn(1)O6 octahedra. Cu(1) is bonded to one O(1) and three equivalent O(2) atoms to form CuO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with nine equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-62°. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mn(1) and one Cu(1) atom to form distorted corner-sharing OMn3Cu trigonal pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mn(1), one Ni(1), and one Cu(1) atom.
Mn3NiCu2O8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. Mn(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Cu(1)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. Both Mn(1)-O(1) bond lengths are 2.04 Å. All Mn(1)-O(2) bond lengths are 1.97 Å. Ni(1) is bonded to six equivalent O(2) atoms to form NiO6 octahedra that share corners with six equivalent Cu(1)O4 tetrahedra and edges with six equivalent Mn(1)O6 octahedra. All Ni(1)-O(2) bond lengths are 2.08 Å. Cu(1) is bonded to one O(1) and three equivalent O(2) atoms to form CuO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with nine equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-62°. The Cu(1)-O(1) bond length is 1.97 Å. All Cu(1)-O(2) bond lengths are 1.99 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mn(1) and one Cu(1) atom to form distorted corner-sharing OMn3Cu trigonal pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mn(1), one Ni(1), and one Cu(1) atom.