Gd2Mn3Sb3O14 crystallizes in the monoclinic C2/m space group. Gd(1) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form GdO8 hexagonal bipyramids that share edges with two equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O8 hexagonal bipyramids, edges with two equivalent Mn(2)O8 hexagonal bipyramids, edges with two equivalent Mn(3)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(1), two equivalent O(2), and four equivalent O(5) atoms to form distorted MnO8 hexagonal bipyramids that share edges with two equivalent Mn(2)O8 hexagonal bipyramids, edges with four equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Sb(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms to form distorted MnO8 hexagonal bipyramids that share edges with two equivalent Mn(1)O8 hexagonal bipyramids, edges with four equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(3)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. In the third Mn site, Mn(3) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form MnO6 octahedra that share corners with two equivalent Sb(2)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Mn(2)O8 hexagonal bipyramids, and edges with four equivalent Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 49-51°. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, corners with two equivalent Sb(2)O6 octahedra, edges with two equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O8 hexagonal bipyramids, and edges with two equivalent Mn(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-49°. In the second Sb site, Sb(2) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Mn(1)O8 hexagonal bipyramids, and edges with four equivalent Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-51°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Gd(1), one Mn(1), and one Mn(2) atom to form OGd2Mn2 tetrahedra that share corners with two equivalent O(3)Gd2MnSb tetrahedra, corners with two equivalent O(2)Mn2Sb2 tetrahedra, corners with four equivalent O(1)Gd2Mn2 tetrahedra, corners with four equivalent O(5)GdMnSb2 tetrahedra,  an edgeedge with one O(3)Gd2MnSb tetrahedra,  an edgeedge with one O(2)Mn2Sb2 tetrahedra, and edges with two equivalent O(5)GdMnSb2 tetrahedra. In the second O site, O(2) is bonded to one Mn(1), one Mn(2), and two equivalent Sb(1) atoms to form distorted OMn2Sb2 tetrahedra that share corners with two equivalent O(1)Gd2Mn2 tetrahedra, corners with four equivalent O(5)GdMnSb2 tetrahedra, corners with four equivalent O(2)Mn2Sb2 tetrahedra,  an edgeedge with one O(1)Gd2Mn2 tetrahedra, and edges with two equivalent O(5)GdMnSb2 tetrahedra. In the third O site, O(3) is bonded to two equivalent Gd(1), one Mn(3), and one Sb(2) atom to form distorted OGd2MnSb tetrahedra that share corners with two equivalent O(1)Gd2Mn2 tetrahedra, corners with four equivalent O(3)Gd2MnSb tetrahedra, corners with four equivalent O(5)GdMnSb2 tetrahedra,  an edgeedge with one O(1)Gd2Mn2 tetrahedra, and edges with two equivalent O(5)GdMnSb2 tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Gd(1), one Mn(2), one Mn(3), and one Sb(1) atom. In the fifth O site, O(5) is bonded to one Gd(1), one Mn(1), one Sb(1), and one Sb(2) atom to form distorted OGdMnSb2 tetrahedra that share corners with two equivalent O(1)Gd2Mn2 tetrahedra, corners with two equivalent O(3)Gd2MnSb tetrahedra, corners with two equivalent O(2)Mn2Sb2 tetrahedra, corners with six equivalent O(5)GdMnSb2 tetrahedra,  an edgeedge with one O(1)Gd2Mn2 tetrahedra,  an edgeedge with one O(3)Gd2MnSb tetrahedra,  an edgeedge with one O(5)GdMnSb2 tetrahedra, and  an edgeedge with one O(2)Mn2Sb2 tetrahedra.
Gd2Mn3Sb3O14 crystallizes in the monoclinic C2/m space group. Gd(1) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form GdO8 hexagonal bipyramids that share edges with two equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O8 hexagonal bipyramids, edges with two equivalent Mn(2)O8 hexagonal bipyramids, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, and edges with two equivalent Sb(2)O6 octahedra. Both Gd(1)-O(1) bond lengths are 2.33 Å. Both Gd(1)-O(3) bond lengths are 2.51 Å. Both Gd(1)-O(4) bond lengths are 2.49 Å. Both Gd(1)-O(5) bond lengths are 2.47 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(5) atoms to form distorted MnO8 hexagonal bipyramids that share edges with two equivalent Mn(2)O8 hexagonal bipyramids, edges with four equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Sb(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Mn(1)-O(1) bond lengths are 2.09 Å. Both Mn(1)-O(2) bond lengths are 2.54 Å. All Mn(1)-O(5) bond lengths are 2.57 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms to form distorted MnO8 hexagonal bipyramids that share edges with two equivalent Mn(1)O8 hexagonal bipyramids, edges with four equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(3)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Mn(2)-O(1) bond lengths are 2.16 Å. Both Mn(2)-O(2) bond lengths are 2.46 Å. All Mn(2)-O(4) bond lengths are 2.59 Å. In the third Mn site, Mn(3) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form MnO6 octahedra that share corners with two equivalent Sb(2)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Mn(2)O8 hexagonal bipyramids, and edges with four equivalent Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 49-51°. Both Mn(3)-O(3) bond lengths are 2.01 Å. All Mn(3)-O(4) bond lengths are 1.98 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, corners with two equivalent Sb(2)O6 octahedra, edges with two equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(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(1)-O(2) bond lengths are 2.02 Å. Both Sb(1)-O(4) bond lengths are 1.97 Å. Both Sb(1)-O(5) bond lengths are 2.00 Å. In the second Sb site, Sb(2) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Mn(1)O8 hexagonal bipyramids, and edges with four equivalent Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-51°. Both Sb(2)-O(3) bond lengths are 1.96 Å. All Sb(2)-O(5) bond lengths are 2.00 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Gd(1), one Mn(1), and one Mn(2) atom to form OGd2Mn2 tetrahedra that share corners with two equivalent O(3)Gd2MnSb tetrahedra, corners with two equivalent O(2)Mn2Sb2 tetrahedra, corners with four equivalent O(1)Gd2Mn2 tetrahedra, corners with four equivalent O(5)GdMnSb2 tetrahedra,  an edgeedge with one O(3)Gd2MnSb tetrahedra,  an edgeedge with one O(2)Mn2Sb2 tetrahedra, and edges with two equivalent O(5)GdMnSb2 tetrahedra. In the second O site, O(2) is bonded to one Mn(1), one Mn(2), and two equivalent Sb(1) atoms to form distorted OMn2Sb2 tetrahedra that share corners with two equivalent O(1)Gd2Mn2 tetrahedra, corners with four equivalent O(5)GdMnSb2 tetrahedra, corners with four equivalent O(2)Mn2Sb2 tetrahedra,  an edgeedge with one O(1)Gd2Mn2 tetrahedra, and edges with two equivalent O(5)GdMnSb2 tetrahedra. In the third O site, O(3) is bonded to two equivalent Gd(1), one Mn(3), and one Sb(2) atom to form distorted OGd2MnSb tetrahedra that share corners with two equivalent O(1)Gd2Mn2 tetrahedra, corners with four equivalent O(3)Gd2MnSb tetrahedra, corners with four equivalent O(5)GdMnSb2 tetrahedra,  an edgeedge with one O(1)Gd2Mn2 tetrahedra, and edges with two equivalent O(5)GdMnSb2 tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Gd(1), one Mn(2), one Mn(3), and one Sb(1) atom. In the fifth O site, O(5) is bonded to one Gd(1), one Mn(1), one Sb(1), and one Sb(2) atom to form distorted OGdMnSb2 tetrahedra that share corners with two equivalent O(1)Gd2Mn2 tetrahedra, corners with two equivalent O(3)Gd2MnSb tetrahedra, corners with two equivalent O(2)Mn2Sb2 tetrahedra, corners with six equivalent O(5)GdMnSb2 tetrahedra,  an edgeedge with one O(1)Gd2Mn2 tetrahedra,  an edgeedge with one O(3)Gd2MnSb tetrahedra,  an edgeedge with one O(5)GdMnSb2 tetrahedra, and  an edgeedge with one O(2)Mn2Sb2 tetrahedra.