Tm2Mn2O7 crystallizes in the cubic Fd-3m space group. Tm(1) is bonded to two equivalent O(2) and six equivalent O(1) atoms to form distorted TmO8 hexagonal bipyramids that share edges with six equivalent Tm(1)O8 hexagonal bipyramids and edges with six equivalent Mn(1)O6 octahedra. Mn(1) is bonded to six equivalent O(1) atoms to form MnO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra and edges with six equivalent Tm(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 49°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tm(1) and two equivalent Mn(1) atoms to form distorted OTm2Mn2 tetrahedra that share corners with two equivalent O(2)Tm4 tetrahedra, corners with twelve equivalent O(1)Tm2Mn2 tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and edges with four equivalent O(1)Tm2Mn2 tetrahedra. In the second O site, O(2) is bonded to four equivalent Tm(1) atoms to form OTm4 tetrahedra that share corners with four equivalent O(2)Tm4 tetrahedra, corners with twelve equivalent O(1)Tm2Mn2 tetrahedra, and edges with six equivalent O(1)Tm2Mn2 tetrahedra.
Tm2Mn2O7 crystallizes in the cubic Fd-3m space group. Tm(1) is bonded to two equivalent O(2) and six equivalent O(1) atoms to form distorted TmO8 hexagonal bipyramids that share edges with six equivalent Tm(1)O8 hexagonal bipyramids and edges with six equivalent Mn(1)O6 octahedra. Both Tm(1)-O(2) bond lengths are 2.12 Å. All Tm(1)-O(1) bond lengths are 2.40 Å. Mn(1) is bonded to six equivalent O(1) atoms to form MnO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra and edges with six equivalent Tm(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 49°. All Mn(1)-O(1) bond lengths are 1.90 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tm(1) and two equivalent Mn(1) atoms to form distorted OTm2Mn2 tetrahedra that share corners with two equivalent O(2)Tm4 tetrahedra, corners with twelve equivalent O(1)Tm2Mn2 tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and edges with four equivalent O(1)Tm2Mn2 tetrahedra. In the second O site, O(2) is bonded to four equivalent Tm(1) atoms to form OTm4 tetrahedra that share corners with four equivalent O(2)Tm4 tetrahedra, corners with twelve equivalent O(1)Tm2Mn2 tetrahedra, and edges with six equivalent O(1)Tm2Mn2 tetrahedra.