CoSe2O5 crystallizes in the orthorhombic Pbcn space group. Co(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form edge-sharing CoO6 octahedra. Se(1) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(3) atom. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Se(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Co(1) and one Se(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Co(1) and one Se(1) atom.
CoSe2O5 crystallizes in the orthorhombic Pbcn space group. Co(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form edge-sharing CoO6 octahedra. Both Co(1)-O(3) bond lengths are 2.08 Å. There are two shorter (2.09 Å) and two longer (2.11 Å) Co(1)-O(2) bond lengths. Se(1) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(3) atom. The Se(1)-O(1) bond length is 1.84 Å. The Se(1)-O(2) bond length is 1.70 Å. The Se(1)-O(3) bond length is 1.68 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Se(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Co(1) and one Se(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Co(1) and one Se(1) atom.