Sr2Fe2TlAlO7 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to one O(3) and four equivalent O(2) atoms to form SrO5 square pyramids that share corners with five equivalent Sr(1)O5 square pyramids, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with four equivalent Sr(1)O5 square pyramids. Fe(1) is bonded to one O(2) and four equivalent O(1) atoms to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Tl(1)O6 octahedra, corners with four equivalent Sr(1)O5 square pyramids, and corners with four equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. Tl(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form distorted TlO6 octahedra that share corners with four equivalent Tl(1)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with eight equivalent Sr(1)O5 square pyramids. The corner-sharing octahedra are not tilted. Al(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Fe(1) and two equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing OAl2Fe2 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to four equivalent Sr(1), one Fe(1), and one Tl(1) atom. In the third O site, O(3) is bonded to two equivalent Sr(1) and four equivalent Tl(1) atoms to form a mixture of corner and edge-sharing OSr2Tl4 octahedra. The corner-sharing octahedra are not tilted.
Sr2Fe2TlAlO7 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to one O(3) and four equivalent O(2) atoms to form SrO5 square pyramids that share corners with five equivalent Sr(1)O5 square pyramids, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with four equivalent Sr(1)O5 square pyramids. The Sr(1)-O(3) bond length is 2.46 Å. All Sr(1)-O(2) bond lengths are 2.67 Å. Fe(1) is bonded to one O(2) and four equivalent O(1) atoms to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Tl(1)O6 octahedra, corners with four equivalent Sr(1)O5 square pyramids, and corners with four equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. The Fe(1)-O(2) bond length is 1.93 Å. All Fe(1)-O(1) bond lengths are 1.97 Å. Tl(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form distorted TlO6 octahedra that share corners with four equivalent Tl(1)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with eight equivalent Sr(1)O5 square pyramids. The corner-sharing octahedra are not tilted. Both Tl(1)-O(2) bond lengths are 2.82 Å. All Tl(1)-O(3) bond lengths are 2.64 Å. Al(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Al(1)-O(1) bond lengths are 2.23 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Fe(1) and two equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing OAl2Fe2 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to four equivalent Sr(1), one Fe(1), and one Tl(1) atom. In the third O site, O(3) is bonded to two equivalent Sr(1) and four equivalent Tl(1) atoms to form a mixture of corner and edge-sharing OSr2Tl4 octahedra. The corner-sharing octahedra are not tilted.