Sr3Fe2Cu2Se2O5 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Fe(1)O5 square pyramids. In the second Sr site, Sr(2) is bonded in a 4-coordinate geometry to four equivalent Se(1) and four equivalent O(2) atoms. Fe(1) is bonded to one O(1) and four equivalent O(2) atoms to form FeO5 square pyramids that share corners with five equivalent Fe(1)O5 square pyramids and faces with four equivalent Sr(1)O12 cuboctahedra. Cu(1) is bonded to four equivalent Se(1) atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. Se(1) is bonded in a 8-coordinate geometry to four equivalent Sr(2) and four equivalent Cu(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent Sr(1) and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms.
Sr3Fe2Cu2Se2O5 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Fe(1)O5 square pyramids. All Sr(1)-O(1) bond lengths are 2.83 Å. There are four shorter (2.94 Å) and four longer (2.95 Å) Sr(1)-O(2) bond lengths. In the second Sr site, Sr(2) is bonded in a 4-coordinate geometry to four equivalent Se(1) and four equivalent O(2) atoms. All Sr(2)-Se(1) bond lengths are 3.22 Å. All Sr(2)-O(2) bond lengths are 2.55 Å. Fe(1) is bonded to one O(1) and four equivalent O(2) atoms to form FeO5 square pyramids that share corners with five equivalent Fe(1)O5 square pyramids and faces with four equivalent Sr(1)O12 cuboctahedra. The Fe(1)-O(1) bond length is 1.90 Å. All Fe(1)-O(2) bond lengths are 2.02 Å. Cu(1) is bonded to four equivalent Se(1) atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. All Cu(1)-Se(1) bond lengths are 2.52 Å. Se(1) is bonded in a 8-coordinate geometry to four equivalent Sr(2) and four equivalent Cu(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent Sr(1) and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms.