MgH2SeO5 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Se(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. H(1) is bonded in a single-bond geometry to one O(3) atom. Se(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SeO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Se(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Se(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to two equivalent Mg(1) and two equivalent H(1) atoms.
MgH2SeO5 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Se(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. Both Mg(1)-O(1) bond lengths are 2.04 Å. Both Mg(1)-O(2) bond lengths are 2.10 Å. Both Mg(1)-O(3) bond lengths are 2.23 Å. H(1) is bonded in a single-bond geometry to one O(3) atom. The H(1)-O(3) bond length is 1.00 Å. Se(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SeO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. Both Se(1)-O(1) bond lengths are 1.66 Å. Both Se(1)-O(2) bond lengths are 1.68 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Se(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Se(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to two equivalent Mg(1) and two equivalent H(1) atoms.