Sr3FeCo(O2Cl)2 crystallizes in the tetragonal I4mm space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to four equivalent O(2), one Cl(1), and four equivalent Cl(2) atoms. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to four equivalent O(1), one Cl(2), and four equivalent Cl(1) atoms. In the third Sr site, Sr(3) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Fe(1) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(1) and one Cl(1) atom. Co(1) is bonded to four equivalent O(2) and one Cl(2) atom to form distorted corner-sharing CoClO4 square pyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(2), two equivalent Sr(3), and two equivalent Fe(1) atoms to form OSr4Fe2 octahedra that share corners with two equivalent O(1)Sr4Fe2 octahedra, corners with six equivalent O(2)Sr4Co2 octahedra,  an edgeedge with one O(2)Sr4Co2 octahedra, edges with two equivalent O(1)Sr4Fe2 octahedra, and faces with four equivalent O(1)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-65°. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(3), and two equivalent Co(1) atoms to form OSr4Co2 octahedra that share corners with two equivalent O(2)Sr4Co2 octahedra, corners with six equivalent O(1)Sr4Fe2 octahedra,  an edgeedge with one O(1)Sr4Fe2 octahedra, edges with two equivalent O(2)Sr4Co2 octahedra, and faces with four equivalent O(2)Sr4Co2 octahedra. The corner-sharing octahedral tilt angles range from 2-65°. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted hexagonal planar geometry to one Sr(1), four equivalent Sr(2), and one Fe(1) atom. In the second Cl site, Cl(2) is bonded in a 6-coordinate geometry to one Sr(2), four equivalent Sr(1), and one Co(1) atom.
Sr3FeCo(O2Cl)2 crystallizes in the tetragonal I4mm space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to four equivalent O(2), one Cl(1), and four equivalent Cl(2) atoms. All Sr(1)-O(2) bond lengths are 2.63 Å. The Sr(1)-Cl(1) bond length is 3.25 Å. All Sr(1)-Cl(2) bond lengths are 3.08 Å. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to four equivalent O(1), one Cl(2), and four equivalent Cl(1) atoms. All Sr(2)-O(1) bond lengths are 2.63 Å. The Sr(2)-Cl(2) bond length is 3.41 Å. All Sr(2)-Cl(1) bond lengths are 3.14 Å. In the third Sr site, Sr(3) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Sr(3)-O(1) bond lengths are 2.73 Å. All Sr(3)-O(2) bond lengths are 2.64 Å. Fe(1) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(1) and one Cl(1) atom. All Fe(1)-O(1) bond lengths are 2.05 Å. The Fe(1)-Cl(1) bond length is 2.98 Å. Co(1) is bonded to four equivalent O(2) and one Cl(2) atom to form distorted corner-sharing CoClO4 square pyramids. All Co(1)-O(2) bond lengths are 2.05 Å. The Co(1)-Cl(2) bond length is 2.66 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(2), two equivalent Sr(3), and two equivalent Fe(1) atoms to form OSr4Fe2 octahedra that share corners with two equivalent O(1)Sr4Fe2 octahedra, corners with six equivalent O(2)Sr4Co2 octahedra,  an edgeedge with one O(2)Sr4Co2 octahedra, edges with two equivalent O(1)Sr4Fe2 octahedra, and faces with four equivalent O(1)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-65°. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(3), and two equivalent Co(1) atoms to form OSr4Co2 octahedra that share corners with two equivalent O(2)Sr4Co2 octahedra, corners with six equivalent O(1)Sr4Fe2 octahedra,  an edgeedge with one O(1)Sr4Fe2 octahedra, edges with two equivalent O(2)Sr4Co2 octahedra, and faces with four equivalent O(2)Sr4Co2 octahedra. The corner-sharing octahedral tilt angles range from 2-65°. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted hexagonal planar geometry to one Sr(1), four equivalent Sr(2), and one Fe(1) atom. In the second Cl site, Cl(2) is bonded in a 6-coordinate geometry to one Sr(2), four equivalent Sr(1), and one Co(1) atom.