Fe(SeO3)2 crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to one O(1), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form edge-sharing FeO6 octahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(2), and one O(3) atom. In the second Se site, Se(2) is bonded in a distorted trigonal non-coplanar geometry to one O(4), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one Se(2) atom. In the second O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(1) and one Se(1) atom. In the third O site, O(2) is bonded in a single-bond geometry to one Se(1) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one Se(1) atom. In the fifth O site, O(4) is bonded in a bent 120 degrees geometry to one Fe(1) and one Se(2) atom. In the sixth O site, O(5) is bonded in a trigonal non-coplanar geometry to two equivalent Fe(1) and one Se(2) atom.
Fe(SeO3)2 crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to one O(1), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form edge-sharing FeO6 octahedra. The Fe(1)-O(1) bond length is 2.07 Å. The Fe(1)-O(3) bond length is 2.04 Å. The Fe(1)-O(4) bond length is 1.96 Å. The Fe(1)-O(6) bond length is 1.98 Å. There is one shorter (2.06 Å) and one longer (2.14 Å) Fe(1)-O(5) bond length. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(2), and one O(3) atom. The Se(1)-O(1) bond length is 1.71 Å. The Se(1)-O(2) bond length is 1.66 Å. The Se(1)-O(3) bond length is 1.72 Å. In the second Se site, Se(2) is bonded in a distorted trigonal non-coplanar geometry to one O(4), one O(5), and one O(6) atom. The Se(2)-O(4) bond length is 1.72 Å. The Se(2)-O(5) bond length is 1.79 Å. The Se(2)-O(6) bond length is 1.71 Å. There are six inequivalent O sites. In the first O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one Se(2) atom. In the second O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(1) and one Se(1) atom. In the third O site, O(2) is bonded in a single-bond geometry to one Se(1) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one Se(1) atom. In the fifth O site, O(4) is bonded in a bent 120 degrees geometry to one Fe(1) and one Se(2) atom. In the sixth O site, O(5) is bonded in a trigonal non-coplanar geometry to two equivalent Fe(1) and one Se(2) atom.