Mg(ClO4)2 crystallizes in the monoclinic P2_1/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 six equivalent Cl(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cl(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cl(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cl(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Cl(1) atom. Cl(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form ClO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-44°.
Mg(ClO4)2 crystallizes in the monoclinic P2_1/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 six equivalent Cl(1)O4 tetrahedra. Both Mg(1)-O(1) bond lengths are 2.10 Å. Both Mg(1)-O(2) bond lengths are 2.13 Å. Both Mg(1)-O(3) bond lengths are 2.11 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cl(1) atom. The O(1)-Cl(1) bond length is 1.46 Å. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cl(1) atom. The O(2)-Cl(1) bond length is 1.46 Å. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cl(1) atom. The O(3)-Cl(1) bond length is 1.48 Å. In the fourth O site, O(4) is bonded in a single-bond geometry to one Cl(1) atom. The O(4)-Cl(1) bond length is 1.42 Å. Cl(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form ClO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-44°.