BaSr(FeO2)4 crystallizes in the orthorhombic Cmc2_1 space group. Ba(1) is bonded in a 10-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), two equivalent O(4), and three equivalent O(5) atoms. Sr(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form corner-sharing FeO4 tetrahedra. In the second Fe site, Fe(2) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form corner-sharing FeO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), and two equivalent Fe(1) atoms. In the second O site, O(4) is bonded to one Ba(1), one Sr(1), and two equivalent Fe(2) atoms to form a mixture of distorted corner and edge-sharing OBaSrFe2 trigonal pyramids. In the third O site, O(5) is bonded in a distorted linear geometry to three equivalent Ba(1) and two equivalent Fe(2) atoms. In the fourth O site, O(1) is bonded to one Ba(1), one Sr(1), and two equivalent Fe(1) atoms to form a mixture of distorted corner and edge-sharing OBaSrFe2 tetrahedra. In the fifth O site, O(2) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(1), one Fe(1), and one Fe(2) atom.
BaSr(FeO2)4 crystallizes in the orthorhombic Cmc2_1 space group. Ba(1) is bonded in a 10-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), two equivalent O(4), and three equivalent O(5) atoms. The Ba(1)-O(3) bond length is 2.78 Å. Both Ba(1)-O(1) bond lengths are 2.67 Å. Both Ba(1)-O(2) bond lengths are 3.09 Å. Both Ba(1)-O(4) bond lengths are 3.04 Å. There is one shorter (2.97 Å) and two longer (3.15 Å) Ba(1)-O(5) bond lengths. Sr(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. The Sr(1)-O(3) bond length is 3.03 Å. Both Sr(1)-O(1) bond lengths are 2.87 Å. Both Sr(1)-O(2) bond lengths are 2.57 Å. Both Sr(1)-O(4) bond lengths are 2.56 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form corner-sharing FeO4 tetrahedra. The Fe(1)-O(2) bond length is 1.92 Å. The Fe(1)-O(3) bond length is 1.87 Å. There is one shorter (1.91 Å) and one longer (1.92 Å) Fe(1)-O(1) bond length. In the second Fe site, Fe(2) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form corner-sharing FeO4 tetrahedra. The Fe(2)-O(2) bond length is 1.91 Å. The Fe(2)-O(5) bond length is 1.91 Å. There is one shorter (1.90 Å) and one longer (1.91 Å) Fe(2)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), and two equivalent Fe(1) atoms. In the second O site, O(4) is bonded to one Ba(1), one Sr(1), and two equivalent Fe(2) atoms to form a mixture of distorted corner and edge-sharing OBaSrFe2 trigonal pyramids. In the third O site, O(5) is bonded in a distorted linear geometry to three equivalent Ba(1) and two equivalent Fe(2) atoms. In the fourth O site, O(1) is bonded to one Ba(1), one Sr(1), and two equivalent Fe(1) atoms to form a mixture of distorted corner and edge-sharing OBaSrFe2 tetrahedra. In the fifth O site, O(2) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(1), one Fe(1), and one Fe(2) atom.