Li3MnCu3O8 crystallizes in the trigonal R-3m space group. Li(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form LiO6 octahedra that share corners with six equivalent Cu(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, and edges with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-9°. Mn(1) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share edges with six equivalent Li(1)O6 octahedra and edges with six equivalent Cu(1)O6 octahedra. Cu(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CuO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, and edges with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-9°. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Li(1) and three equivalent Cu(1) atoms to form OLi3Cu3 octahedra that share corners with six equivalent O(1)Li3Cu3 octahedra and edges with twelve equivalent O(2)Li2MnCu2 square pyramids. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to two equivalent Li(1), one Mn(1), and two equivalent Cu(1) atoms to form OLi2MnCu2 square pyramids that share corners with nine equivalent O(2)Li2MnCu2 square pyramids, edges with four equivalent O(1)Li3Cu3 octahedra, and edges with four equivalent O(2)Li2MnCu2 square pyramids.
Li3MnCu3O8 crystallizes in the trigonal R-3m space group. Li(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form LiO6 octahedra that share corners with six equivalent Cu(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, and edges with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-9°. Both Li(1)-O(1) bond lengths are 2.18 Å. All Li(1)-O(2) bond lengths are 2.14 Å. Mn(1) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share edges with six equivalent Li(1)O6 octahedra and edges with six equivalent Cu(1)O6 octahedra. All Mn(1)-O(2) bond lengths are 1.92 Å. Cu(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CuO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, and edges with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-9°. Both Cu(1)-O(1) bond lengths are 2.00 Å. All Cu(1)-O(2) bond lengths are 2.05 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Li(1) and three equivalent Cu(1) atoms to form OLi3Cu3 octahedra that share corners with six equivalent O(1)Li3Cu3 octahedra and edges with twelve equivalent O(2)Li2MnCu2 square pyramids. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to two equivalent Li(1), one Mn(1), and two equivalent Cu(1) atoms to form OLi2MnCu2 square pyramids that share corners with nine equivalent O(2)Li2MnCu2 square pyramids, edges with four equivalent O(1)Li3Cu3 octahedra, and edges with four equivalent O(2)Li2MnCu2 square pyramids.