Fe(Se2O5)2 crystallizes in the orthorhombic Pnc2 space group. Fe(1) is bonded in an octahedral geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(1), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Se(1) and one Se(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Se(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to two equivalent Se(1) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one Se(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Fe(1) and one Se(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to two equivalent Se(2) atoms.
Fe(Se2O5)2 crystallizes in the orthorhombic Pnc2 space group. Fe(1) is bonded in an octahedral geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Both Fe(1)-O(2) bond lengths are 2.08 Å. Both Fe(1)-O(4) bond lengths are 2.02 Å. Both Fe(1)-O(5) bond lengths are 2.02 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Se(1)-O(1) bond length is 2.38 Å. The Se(1)-O(2) bond length is 1.71 Å. The Se(1)-O(3) bond length is 1.87 Å. The Se(1)-O(4) bond length is 1.68 Å. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(1), one O(5), and one O(6) atom. The Se(2)-O(1) bond length is 1.68 Å. The Se(2)-O(5) bond length is 1.70 Å. The Se(2)-O(6) bond length is 1.89 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Se(1) and one Se(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Se(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to two equivalent Se(1) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one Se(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Fe(1) and one Se(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to two equivalent Se(2) atoms.