Tb2MnSbO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms to form distorted TbO8 hexagonal bipyramids that share edges with two equivalent Tb(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. In the second Tb site, Tb(2) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms. Mn(1) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, and edges with two equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 51-53°. Sb(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-53°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with two equivalent O(3)Tb2Mn2 tetrahedra, corners with two equivalent O(2)Tb2Sb2 tetrahedra, corners with four equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(3)Tb2Mn2 tetrahedra,  an edgeedge with one O(2)Tb2Sb2 tetrahedra, and edges with four equivalent O(4)Tb2MnSb tetrahedra. In the second O site, O(2) is bonded to two equivalent Tb(1) and two equivalent Sb(1) atoms to form distorted OTb2Sb2 tetrahedra that share corners with two equivalent O(1)Tb4 tetrahedra, corners with four equivalent O(2)Tb2Sb2 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with four equivalent O(4)Tb2MnSb tetrahedra. In the third O site, O(3) is bonded to two equivalent Tb(2) and two equivalent Mn(1) atoms to form distorted OTb2Mn2 tetrahedra that share corners with two equivalent O(1)Tb4 tetrahedra, corners with four equivalent O(3)Tb2Mn2 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with four equivalent O(4)Tb2MnSb tetrahedra. In the fourth O site, O(4) is bonded to one Tb(1), one Tb(2), one Mn(1), and one Sb(1) atom to form distorted OTb2MnSb tetrahedra that share corners with two equivalent O(3)Tb2Mn2 tetrahedra, corners with two equivalent O(2)Tb2Sb2 tetrahedra, corners with two equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(3)Tb2Mn2 tetrahedra,  an edgeedge with one O(2)Tb2Sb2 tetrahedra,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with two equivalent O(4)Tb2MnSb tetrahedra.
Tb2MnSbO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms to form distorted TbO8 hexagonal bipyramids that share edges with two equivalent Tb(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Tb(1)-O(1) bond lengths are 2.22 Å. Both Tb(1)-O(2) bond lengths are 2.53 Å. All Tb(1)-O(4) bond lengths are 2.50 Å. In the second Tb site, Tb(2) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms. Both Tb(2)-O(1) bond lengths are 2.27 Å. Both Tb(2)-O(3) bond lengths are 2.56 Å. All Tb(2)-O(4) bond lengths are 2.48 Å. Mn(1) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, and edges with two equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 51-53°. Both Mn(1)-O(3) bond lengths are 1.98 Å. All Mn(1)-O(4) bond lengths are 2.10 Å. Sb(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-53°. Both Sb(1)-O(2) bond lengths are 2.04 Å. All Sb(1)-O(4) bond lengths are 1.99 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with two equivalent O(3)Tb2Mn2 tetrahedra, corners with two equivalent O(2)Tb2Sb2 tetrahedra, corners with four equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(3)Tb2Mn2 tetrahedra,  an edgeedge with one O(2)Tb2Sb2 tetrahedra, and edges with four equivalent O(4)Tb2MnSb tetrahedra. In the second O site, O(2) is bonded to two equivalent Tb(1) and two equivalent Sb(1) atoms to form distorted OTb2Sb2 tetrahedra that share corners with two equivalent O(1)Tb4 tetrahedra, corners with four equivalent O(2)Tb2Sb2 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with four equivalent O(4)Tb2MnSb tetrahedra. In the third O site, O(3) is bonded to two equivalent Tb(2) and two equivalent Mn(1) atoms to form distorted OTb2Mn2 tetrahedra that share corners with two equivalent O(1)Tb4 tetrahedra, corners with four equivalent O(3)Tb2Mn2 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with four equivalent O(4)Tb2MnSb tetrahedra. In the fourth O site, O(4) is bonded to one Tb(1), one Tb(2), one Mn(1), and one Sb(1) atom to form distorted OTb2MnSb tetrahedra that share corners with two equivalent O(3)Tb2Mn2 tetrahedra, corners with two equivalent O(2)Tb2Sb2 tetrahedra, corners with two equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(4)Tb2MnSb tetrahedra,  an edgeedge with one O(3)Tb2Mn2 tetrahedra,  an edgeedge with one O(2)Tb2Sb2 tetrahedra,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with two equivalent O(4)Tb2MnSb tetrahedra.