MgH8(O6Cl)2 is alpha structured and crystallizes in the monoclinic C2 space group. The structure is zero-dimensional and consists of two MgH8(O6Cl)2 clusters. Mg(1) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent Cl(1)O4 tetrahedra. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Mg(1) and one Cl(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Cl(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent H(3) atoms. In the fifth O site, O(5) is bonded in a single-bond geometry to one Cl(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Cl(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent H(4) atoms. Cl(1) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form ClO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°.
MgH8(O6Cl)2 is alpha structured and crystallizes in the monoclinic C2 space group. The structure is zero-dimensional and consists of two MgH8(O6Cl)2 clusters. Mg(1) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent Cl(1)O4 tetrahedra. The Mg(1)-O(4) bond length is 2.05 Å. The Mg(1)-O(7) bond length is 2.07 Å. Both Mg(1)-O(1) bond lengths are 2.10 Å. Both Mg(1)-O(2) bond lengths are 2.18 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. The H(2)-O(1) bond length is 0.98 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) atom. The H(3)-O(4) bond length is 0.98 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(7) atom. The H(4)-O(7) bond length is 0.98 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Mg(1) and one Cl(1) atom. The O(2)-Cl(1) bond length is 1.50 Å. In the third O site, O(3) is bonded in a single-bond geometry to one Cl(1) atom. The O(3)-Cl(1) bond length is 1.44 Å. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent H(3) atoms. In the fifth O site, O(5) is bonded in a single-bond geometry to one Cl(1) atom. The O(5)-Cl(1) bond length is 1.47 Å. In the sixth O site, O(6) is bonded in a single-bond geometry to one Cl(1) atom. The O(6)-Cl(1) bond length is 1.44 Å. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent H(4) atoms. Cl(1) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form ClO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°.