Sr3Mg(FeO3)2 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 1-coordinate geometry to four equivalent O(2) and five equivalent O(1) atoms. In the second Sr site, Sr(2) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. Mg(1) is bonded in a 10-coordinate geometry to two equivalent Fe(1) and eight equivalent O(2) atoms. Fe(1) is bonded in a 5-coordinate geometry to one Mg(1), one O(1), and four equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to five equivalent Sr(1) and one Fe(1) atom. In the second O site, O(2) is bonded in a 8-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Mg(1), and two equivalent Fe(1) atoms.
Sr3Mg(FeO3)2 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 1-coordinate geometry to four equivalent O(2) and five equivalent O(1) atoms. All Sr(1)-O(2) bond lengths are 3.01 Å. There is one shorter (2.39 Å) and four longer (2.93 Å) Sr(1)-O(1) bond lengths. In the second Sr site, Sr(2) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. All Sr(2)-O(2) bond lengths are 2.54 Å. Mg(1) is bonded in a 10-coordinate geometry to two equivalent Fe(1) and eight equivalent O(2) atoms. Both Mg(1)-Fe(1) bond lengths are 2.42 Å. All Mg(1)-O(2) bond lengths are 2.54 Å. Fe(1) is bonded in a 5-coordinate geometry to one Mg(1), one O(1), and four equivalent O(2) atoms. The Fe(1)-O(1) bond length is 1.86 Å. All Fe(1)-O(2) bond lengths are 2.23 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to five equivalent Sr(1) and one Fe(1) atom. In the second O site, O(2) is bonded in a 8-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Mg(1), and two equivalent Fe(1) atoms.