La3Mn2Sb3O14 crystallizes in the trigonal R-3m space group. La(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to six equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the second Mn site, Mn(2) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted MnO8 hexagonal bipyramids that share edges with six equivalent Sb(1)O6 octahedra. Sb(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form SbO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, and edges with two equivalent Mn(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 42-55°. There are three inequivalent O sites. In the first O site, O(3) is bonded to two equivalent La(1), one Mn(1), and one Sb(1) atom to form distorted OLa2MnSb tetrahedra that share corners with two equivalent O(1)La3Mn tetrahedra, corners with eight equivalent O(3)La2MnSb tetrahedra, corners with four equivalent O(2)LaMnSb2 trigonal pyramids,  an edgeedge with one O(1)La3Mn tetrahedra, edges with two equivalent O(3)La2MnSb tetrahedra, and edges with two equivalent O(2)LaMnSb2 trigonal pyramids. In the second O site, O(1) is bonded to three equivalent La(1) and one Mn(2) atom to form OLa3Mn tetrahedra that share corners with four equivalent O(1)La3Mn tetrahedra, corners with six equivalent O(3)La2MnSb tetrahedra, corners with six equivalent O(2)LaMnSb2 trigonal pyramids, edges with three equivalent O(3)La2MnSb tetrahedra, and edges with three equivalent O(2)LaMnSb2 trigonal pyramids. In the third O site, O(2) is bonded to one La(1), one Mn(2), and two equivalent Sb(1) atoms to form distorted OLaMnSb2 trigonal pyramids that share corners with two equivalent O(1)La3Mn tetrahedra, corners with four equivalent O(3)La2MnSb tetrahedra, corners with eight equivalent O(2)LaMnSb2 trigonal pyramids,  an edgeedge with one O(1)La3Mn tetrahedra, edges with two equivalent O(3)La2MnSb tetrahedra, and edges with two equivalent O(2)LaMnSb2 trigonal pyramids.
La3Mn2Sb3O14 crystallizes in the trigonal R-3m space group. La(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Both La(1)-O(1) bond lengths are 2.39 Å. Both La(1)-O(2) bond lengths are 2.69 Å. All La(1)-O(3) bond lengths are 2.56 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to six equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Mn(1)-O(3) bond lengths are 2.21 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted MnO8 hexagonal bipyramids that share edges with six equivalent Sb(1)O6 octahedra. Both Mn(2)-O(1) bond lengths are 2.06 Å. All Mn(2)-O(2) bond lengths are 2.67 Å. Sb(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form SbO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, and edges with two equivalent Mn(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 42-55°. Both Sb(1)-O(3) bond lengths are 1.97 Å. All Sb(1)-O(2) bond lengths are 2.05 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded to two equivalent La(1), one Mn(1), and one Sb(1) atom to form distorted OLa2MnSb tetrahedra that share corners with two equivalent O(1)La3Mn tetrahedra, corners with eight equivalent O(3)La2MnSb tetrahedra, corners with four equivalent O(2)LaMnSb2 trigonal pyramids,  an edgeedge with one O(1)La3Mn tetrahedra, edges with two equivalent O(3)La2MnSb tetrahedra, and edges with two equivalent O(2)LaMnSb2 trigonal pyramids. In the second O site, O(1) is bonded to three equivalent La(1) and one Mn(2) atom to form OLa3Mn tetrahedra that share corners with four equivalent O(1)La3Mn tetrahedra, corners with six equivalent O(3)La2MnSb tetrahedra, corners with six equivalent O(2)LaMnSb2 trigonal pyramids, edges with three equivalent O(3)La2MnSb tetrahedra, and edges with three equivalent O(2)LaMnSb2 trigonal pyramids. In the third O site, O(2) is bonded to one La(1), one Mn(2), and two equivalent Sb(1) atoms to form distorted OLaMnSb2 trigonal pyramids that share corners with two equivalent O(1)La3Mn tetrahedra, corners with four equivalent O(3)La2MnSb tetrahedra, corners with eight equivalent O(2)LaMnSb2 trigonal pyramids,  an edgeedge with one O(1)La3Mn tetrahedra, edges with two equivalent O(3)La2MnSb tetrahedra, and edges with two equivalent O(2)LaMnSb2 trigonal pyramids.