Sr3Fe2O4F4 crystallizes in the tetragonal I-4m2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent F(1) atoms to form SrO8F4 cuboctahedra that share corners with four equivalent Sr(1)O8F4 cuboctahedra, faces with four equivalent Sr(1)O8F4 cuboctahedra, and faces with eight equivalent Fe(1)O4F2 octahedra. In the second Sr site, Sr(2) is bonded in a distorted q6 geometry to two equivalent O(1), two equivalent O(2), two equivalent F(3), and four equivalent F(2) atoms. Fe(1) is bonded to two equivalent O(1), two equivalent O(2), one F(1), and one F(2) atom to form FeO4F2 octahedra that share corners with five equivalent Fe(1)O4F2 octahedra and faces with four equivalent Sr(1)O8F4 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-6°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(2)Sr4Fe2 octahedra, corners with four equivalent F(1)Sr4Fe2 octahedra, corners with six equivalent O(1)Sr4Fe2 octahedra, corners with four equivalent F(3)Sr4 tetrahedra,  an edgeedge with one O(2)Sr4Fe2 octahedra, edges with two equivalent O(1)Sr4Fe2 octahedra, faces with two equivalent F(1)Sr4Fe2 octahedra, and faces with four equivalent O(2)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 1-61°. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(1)Sr4Fe2 octahedra, corners with four equivalent F(1)Sr4Fe2 octahedra, corners with six equivalent O(2)Sr4Fe2 octahedra, corners with two equivalent F(3)Sr4 tetrahedra,  an edgeedge with one O(1)Sr4Fe2 octahedra, edges with two equivalent O(2)Sr4Fe2 octahedra,  an edgeedge with one F(3)Sr4 tetrahedra, faces with two equivalent F(1)Sr4Fe2 octahedra, and faces with four equivalent O(1)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-60°. There are three inequivalent F sites. In the first F site, F(1) is bonded to four equivalent Sr(1) and two equivalent Fe(1) atoms to form distorted FSr4Fe2 octahedra that share corners with four equivalent F(1)Sr4Fe2 octahedra, corners with eight equivalent O(1)Sr4Fe2 octahedra, corners with eight equivalent O(2)Sr4Fe2 octahedra, edges with four equivalent F(1)Sr4Fe2 octahedra, faces with four equivalent O(1)Sr4Fe2 octahedra, and faces with four equivalent O(2)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the second F site, F(2) is bonded in a distorted single-bond geometry to four equivalent Sr(2) and one Fe(1) atom. In the third F site, F(3) is bonded to four equivalent Sr(2) atoms to form FSr4 tetrahedra that share corners with four equivalent O(2)Sr4Fe2 octahedra, corners with eight equivalent O(1)Sr4Fe2 octahedra, corners with four equivalent F(3)Sr4 tetrahedra, and edges with two equivalent O(2)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-63°.
Sr3Fe2O4F4 crystallizes in the tetragonal I-4m2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent F(1) atoms to form SrO8F4 cuboctahedra that share corners with four equivalent Sr(1)O8F4 cuboctahedra, faces with four equivalent Sr(1)O8F4 cuboctahedra, and faces with eight equivalent Fe(1)O4F2 octahedra. All Sr(1)-O(1) bond lengths are 2.87 Å. All Sr(1)-O(2) bond lengths are 2.79 Å. All Sr(1)-F(1) bond lengths are 2.81 Å. In the second Sr site, Sr(2) is bonded in a distorted q6 geometry to two equivalent O(1), two equivalent O(2), two equivalent F(3), and four equivalent F(2) atoms. Both Sr(2)-O(1) bond lengths are 2.69 Å. Both Sr(2)-O(2) bond lengths are 2.76 Å. Both Sr(2)-F(3) bond lengths are 2.66 Å. All Sr(2)-F(2) bond lengths are 2.81 Å. Fe(1) is bonded to two equivalent O(1), two equivalent O(2), one F(1), and one F(2) atom to form FeO4F2 octahedra that share corners with five equivalent Fe(1)O4F2 octahedra and faces with four equivalent Sr(1)O8F4 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-6°. Both Fe(1)-O(1) bond lengths are 1.98 Å. Both Fe(1)-O(2) bond lengths are 1.99 Å. The Fe(1)-F(1) bond length is 2.06 Å. The Fe(1)-F(2) bond length is 2.01 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(2)Sr4Fe2 octahedra, corners with four equivalent F(1)Sr4Fe2 octahedra, corners with six equivalent O(1)Sr4Fe2 octahedra, corners with four equivalent F(3)Sr4 tetrahedra,  an edgeedge with one O(2)Sr4Fe2 octahedra, edges with two equivalent O(1)Sr4Fe2 octahedra, faces with two equivalent F(1)Sr4Fe2 octahedra, and faces with four equivalent O(2)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 1-61°. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(1)Sr4Fe2 octahedra, corners with four equivalent F(1)Sr4Fe2 octahedra, corners with six equivalent O(2)Sr4Fe2 octahedra, corners with two equivalent F(3)Sr4 tetrahedra,  an edgeedge with one O(1)Sr4Fe2 octahedra, edges with two equivalent O(2)Sr4Fe2 octahedra,  an edgeedge with one F(3)Sr4 tetrahedra, faces with two equivalent F(1)Sr4Fe2 octahedra, and faces with four equivalent O(1)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-60°. There are three inequivalent F sites. In the first F site, F(1) is bonded to four equivalent Sr(1) and two equivalent Fe(1) atoms to form distorted FSr4Fe2 octahedra that share corners with four equivalent F(1)Sr4Fe2 octahedra, corners with eight equivalent O(1)Sr4Fe2 octahedra, corners with eight equivalent O(2)Sr4Fe2 octahedra, edges with four equivalent F(1)Sr4Fe2 octahedra, faces with four equivalent O(1)Sr4Fe2 octahedra, and faces with four equivalent O(2)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the second F site, F(2) is bonded in a distorted single-bond geometry to four equivalent Sr(2) and one Fe(1) atom. In the third F site, F(3) is bonded to four equivalent Sr(2) atoms to form FSr4 tetrahedra that share corners with four equivalent O(2)Sr4Fe2 octahedra, corners with eight equivalent O(1)Sr4Fe2 octahedra, corners with four equivalent F(3)Sr4 tetrahedra, and edges with two equivalent O(2)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-63°.