Tb2Mn3Sb3O14 crystallizes in the monoclinic C2/m space group. Tb(1) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted TbO8 hexagonal bipyramids that share edges with two equivalent Tb(1)O8 hexagonal bipyramids, edges with two equivalent Mn(2)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, and edges with two equivalent Sb(2)O6 octahedra. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MnO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra, and edges with four equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 49-54°. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(3), and four equivalent O(5) atoms to form distorted MnO8 hexagonal bipyramids that share edges with four equivalent Tb(1)O8 hexagonal bipyramids, edges with two equivalent Sb(1)O6 octahedra, and edges with four equivalent Sb(2)O6 octahedra. In the third Mn site, Mn(3) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to two equivalent O(2) and four equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra, edges with two equivalent Mn(2)O8 hexagonal bipyramids, and edges with four equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-54°. In the second Sb site, Sb(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, corners with two equivalent Sb(2)O6 octahedra, edges with two equivalent Tb(1)O8 hexagonal bipyramids, and edges with two equivalent Mn(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-49°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1), one Mn(2), and one Mn(3) atom to form OTb2Mn2 tetrahedra that share corners with two equivalent O(2)Tb2MnSb tetrahedra, corners with four equivalent O(1)Tb2Mn2 tetrahedra, corners with four equivalent O(5)TbMnSb2 tetrahedra,  an edgeedge with one O(2)Tb2MnSb tetrahedra, and edges with two equivalent O(5)TbMnSb2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Tb(1), one Mn(1), and one Sb(1) atom to form distorted OTb2MnSb tetrahedra that share corners with two equivalent O(1)Tb2Mn2 tetrahedra, corners with four equivalent O(2)Tb2MnSb tetrahedra, corners with four equivalent O(5)TbMnSb2 tetrahedra,  an edgeedge with one O(1)Tb2Mn2 tetrahedra, and edges with two equivalent O(5)TbMnSb2 tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mn(2), one Mn(3), and two equivalent Sb(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Tb(1), one Mn(1), one Mn(3), and one Sb(2) atom. In the fifth O site, O(5) is bonded to one Tb(1), one Mn(2), one Sb(1), and one Sb(2) atom to form distorted OTbMnSb2 tetrahedra that share corners with two equivalent O(1)Tb2Mn2 tetrahedra, corners with two equivalent O(2)Tb2MnSb tetrahedra, corners with six equivalent O(5)TbMnSb2 tetrahedra,  an edgeedge with one O(1)Tb2Mn2 tetrahedra,  an edgeedge with one O(2)Tb2MnSb tetrahedra, and  an edgeedge with one O(5)TbMnSb2 tetrahedra.
Tb2Mn3Sb3O14 crystallizes in the monoclinic C2/m space group. Tb(1) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted TbO8 hexagonal bipyramids that share edges with two equivalent Tb(1)O8 hexagonal bipyramids, edges with two equivalent Mn(2)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, and edges with two equivalent Sb(2)O6 octahedra. Both Tb(1)-O(1) bond lengths are 2.29 Å. Both Tb(1)-O(2) bond lengths are 2.46 Å. Both Tb(1)-O(4) bond lengths are 2.53 Å. Both Tb(1)-O(5) bond lengths are 2.52 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MnO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra, and edges with four equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 49-54°. Both Mn(1)-O(2) bond lengths are 2.15 Å. All Mn(1)-O(4) bond lengths are 1.98 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(3), and four equivalent O(5) atoms to form distorted MnO8 hexagonal bipyramids that share edges with four equivalent Tb(1)O8 hexagonal bipyramids, edges with two equivalent Sb(1)O6 octahedra, and edges with four equivalent Sb(2)O6 octahedra. Both Mn(2)-O(1) bond lengths are 2.13 Å. Both Mn(2)-O(3) bond lengths are 2.61 Å. All Mn(2)-O(5) bond lengths are 2.56 Å. In the third Mn site, Mn(3) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms. Both Mn(3)-O(1) bond lengths are 2.24 Å. Both Mn(3)-O(3) bond lengths are 2.45 Å. All Mn(3)-O(4) bond lengths are 2.58 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to two equivalent O(2) and four equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra, edges with two equivalent Mn(2)O8 hexagonal bipyramids, and edges with four equivalent Tb(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-54°. Both Sb(1)-O(2) bond lengths are 1.95 Å. All Sb(1)-O(5) bond lengths are 2.02 Å. In the second Sb site, Sb(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, corners with two equivalent Sb(2)O6 octahedra, edges with two equivalent Tb(1)O8 hexagonal bipyramids, and edges with two equivalent Mn(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-49°. Both Sb(2)-O(3) bond lengths are 2.01 Å. Both Sb(2)-O(4) bond lengths are 1.98 Å. Both Sb(2)-O(5) bond lengths are 2.01 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1), one Mn(2), and one Mn(3) atom to form OTb2Mn2 tetrahedra that share corners with two equivalent O(2)Tb2MnSb tetrahedra, corners with four equivalent O(1)Tb2Mn2 tetrahedra, corners with four equivalent O(5)TbMnSb2 tetrahedra,  an edgeedge with one O(2)Tb2MnSb tetrahedra, and edges with two equivalent O(5)TbMnSb2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Tb(1), one Mn(1), and one Sb(1) atom to form distorted OTb2MnSb tetrahedra that share corners with two equivalent O(1)Tb2Mn2 tetrahedra, corners with four equivalent O(2)Tb2MnSb tetrahedra, corners with four equivalent O(5)TbMnSb2 tetrahedra,  an edgeedge with one O(1)Tb2Mn2 tetrahedra, and edges with two equivalent O(5)TbMnSb2 tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mn(2), one Mn(3), and two equivalent Sb(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Tb(1), one Mn(1), one Mn(3), and one Sb(2) atom. In the fifth O site, O(5) is bonded to one Tb(1), one Mn(2), one Sb(1), and one Sb(2) atom to form distorted OTbMnSb2 tetrahedra that share corners with two equivalent O(1)Tb2Mn2 tetrahedra, corners with two equivalent O(2)Tb2MnSb tetrahedra, corners with six equivalent O(5)TbMnSb2 tetrahedra,  an edgeedge with one O(1)Tb2Mn2 tetrahedra,  an edgeedge with one O(2)Tb2MnSb tetrahedra, and  an edgeedge with one O(5)TbMnSb2 tetrahedra.