CaSeO3 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form corner-sharing CaO6 octahedra. The corner-sharing octahedral tilt angles range from 57-61°. Se(1) is bonded in a trigonal non-coplanar geometry to one O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to two equivalent Ca(1) and one Se(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Ca(1) and one Se(1) atom.
CaSeO3 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form corner-sharing CaO6 octahedra. The corner-sharing octahedral tilt angles range from 57-61°. Both Ca(1)-O(1) bond lengths are 2.41 Å. There are two shorter (2.35 Å) and two longer (2.41 Å) Ca(1)-O(2) bond lengths. Se(1) is bonded in a trigonal non-coplanar geometry to one O(1) and two equivalent O(2) atoms. The Se(1)-O(1) bond length is 1.71 Å. Both Se(1)-O(2) bond lengths are 1.72 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to two equivalent Ca(1) and one Se(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Ca(1) and one Se(1) atom.