Gd2MnSbO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms to form distorted GdO8 hexagonal bipyramids that share edges with two equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. In the second Gd site, Gd(2) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms. 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 Mn(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, and edges with two equivalent Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 50-52°. Sb(1) is bonded to two equivalent O(3) 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 Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-52°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Gd(1) and two equivalent Gd(2) atoms to form OGd4 tetrahedra that share corners with two equivalent O(2)Gd2Mn2 tetrahedra, corners with two equivalent O(3)Gd2Sb2 tetrahedra, corners with four equivalent O(1)Gd4 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(2)Gd2Mn2 tetrahedra,  an edgeedge with one O(3)Gd2Sb2 tetrahedra, and edges with four equivalent O(4)Gd2MnSb tetrahedra. In the second O site, O(2) is bonded to two equivalent Gd(2) and two equivalent Mn(1) atoms to form distorted OGd2Mn2 tetrahedra that share corners with two equivalent O(1)Gd4 tetrahedra, corners with four equivalent O(2)Gd2Mn2 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(1)Gd4 tetrahedra, and edges with four equivalent O(4)Gd2MnSb tetrahedra. In the third O site, O(3) is bonded to two equivalent Gd(1) and two equivalent Sb(1) atoms to form distorted OGd2Sb2 tetrahedra that share corners with two equivalent O(1)Gd4 tetrahedra, corners with four equivalent O(3)Gd2Sb2 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(1)Gd4 tetrahedra, and edges with four equivalent O(4)Gd2MnSb tetrahedra. In the fourth O site, O(4) is bonded to one Gd(1), one Gd(2), one Mn(1), and one Sb(1) atom to form distorted OGd2MnSb tetrahedra that share corners with two equivalent O(2)Gd2Mn2 tetrahedra, corners with two equivalent O(3)Gd2Sb2 tetrahedra, corners with two equivalent O(1)Gd4 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(2)Gd2Mn2 tetrahedra,  an edgeedge with one O(3)Gd2Sb2 tetrahedra,  an edgeedge with one O(1)Gd4 tetrahedra, and edges with two equivalent O(4)Gd2MnSb tetrahedra.
Gd2MnSbO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to two equivalent O(1), two equivalent O(3), and four equivalent O(4) atoms to form distorted GdO8 hexagonal bipyramids that share edges with two equivalent Gd(1)O8 hexagonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Gd(1)-O(1) bond lengths are 2.24 Å. Both Gd(1)-O(3) bond lengths are 2.55 Å. All Gd(1)-O(4) bond lengths are 2.53 Å. In the second Gd site, Gd(2) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(4) atoms. Both Gd(2)-O(1) bond lengths are 2.28 Å. Both Gd(2)-O(2) bond lengths are 2.59 Å. All Gd(2)-O(4) bond lengths are 2.50 Å. 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 Mn(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, and edges with two equivalent Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 50-52°. Both Mn(1)-O(2) bond lengths are 1.98 Å. All Mn(1)-O(4) bond lengths are 2.11 Å. Sb(1) is bonded to two equivalent O(3) 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 Gd(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 47-52°. Both Sb(1)-O(3) bond lengths are 2.05 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 Gd(1) and two equivalent Gd(2) atoms to form OGd4 tetrahedra that share corners with two equivalent O(2)Gd2Mn2 tetrahedra, corners with two equivalent O(3)Gd2Sb2 tetrahedra, corners with four equivalent O(1)Gd4 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(2)Gd2Mn2 tetrahedra,  an edgeedge with one O(3)Gd2Sb2 tetrahedra, and edges with four equivalent O(4)Gd2MnSb tetrahedra. In the second O site, O(2) is bonded to two equivalent Gd(2) and two equivalent Mn(1) atoms to form distorted OGd2Mn2 tetrahedra that share corners with two equivalent O(1)Gd4 tetrahedra, corners with four equivalent O(2)Gd2Mn2 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(1)Gd4 tetrahedra, and edges with four equivalent O(4)Gd2MnSb tetrahedra. In the third O site, O(3) is bonded to two equivalent Gd(1) and two equivalent Sb(1) atoms to form distorted OGd2Sb2 tetrahedra that share corners with two equivalent O(1)Gd4 tetrahedra, corners with four equivalent O(3)Gd2Sb2 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(1)Gd4 tetrahedra, and edges with four equivalent O(4)Gd2MnSb tetrahedra. In the fourth O site, O(4) is bonded to one Gd(1), one Gd(2), one Mn(1), and one Sb(1) atom to form distorted OGd2MnSb tetrahedra that share corners with two equivalent O(2)Gd2Mn2 tetrahedra, corners with two equivalent O(3)Gd2Sb2 tetrahedra, corners with two equivalent O(1)Gd4 tetrahedra, corners with eight equivalent O(4)Gd2MnSb tetrahedra,  an edgeedge with one O(2)Gd2Mn2 tetrahedra,  an edgeedge with one O(3)Gd2Sb2 tetrahedra,  an edgeedge with one O(1)Gd4 tetrahedra, and edges with two equivalent O(4)Gd2MnSb tetrahedra.