Sr3MgFe2Cu2Se2O5 crystallizes in the orthorhombic Immm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 4-coordinate geometry to four equivalent Se(1), two equivalent O(1), and two equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded to two equivalent Mg(1) and four equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing SrMg2O4 octahedra. The corner-sharing octahedra are not tilted. Mg(1) is bonded in a square co-planar geometry to two equivalent Sr(2), two equivalent O(1), and two equivalent O(2) atoms. Fe(1) is bonded in a 6-coordinate geometry to one Se(1), one O(2), two equivalent O(1), and two equivalent O(3) atoms. Cu(1) is bonded in a 2-coordinate geometry to four equivalent Se(1) atoms. Se(1) is bonded in a 9-coordinate geometry to four equivalent Sr(1), one Fe(1), and four equivalent Cu(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Sr(1), one Mg(1), and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form a mixture of corner and edge-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-11°.
Sr3MgFe2Cu2Se2O5 crystallizes in the orthorhombic Immm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 4-coordinate geometry to four equivalent Se(1), two equivalent O(1), and two equivalent O(3) atoms. All Sr(1)-Se(1) bond lengths are 3.53 Å. Both Sr(1)-O(1) bond lengths are 2.93 Å. Both Sr(1)-O(3) bond lengths are 2.49 Å. In the second Sr site, Sr(2) is bonded to two equivalent Mg(1) and four equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing SrMg2O4 octahedra. The corner-sharing octahedra are not tilted. Both Sr(2)-Mg(1) bond lengths are 2.55 Å. All Sr(2)-O(3) bond lengths are 2.72 Å. Mg(1) is bonded in a square co-planar geometry to two equivalent Sr(2), two equivalent O(1), and two equivalent O(2) atoms. Both Mg(1)-O(1) bond lengths are 1.98 Å. Both Mg(1)-O(2) bond lengths are 1.96 Å. Fe(1) is bonded in a 6-coordinate geometry to one Se(1), one O(2), two equivalent O(1), and two equivalent O(3) atoms. The Fe(1)-Se(1) bond length is 2.74 Å. The Fe(1)-O(2) bond length is 2.14 Å. Both Fe(1)-O(1) bond lengths are 1.97 Å. Both Fe(1)-O(3) bond lengths are 2.56 Å. Cu(1) is bonded in a 2-coordinate geometry to four equivalent Se(1) atoms. There are two shorter (2.36 Å) and two longer (2.93 Å) Cu(1)-Se(1) bond lengths. Se(1) is bonded in a 9-coordinate geometry to four equivalent Sr(1), one Fe(1), and four equivalent Cu(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Sr(1), one Mg(1), and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form a mixture of corner and edge-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-11°.