K2MgH8(SO6)2 crystallizes in the monoclinic C2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(13), one O(3), one O(5), and one O(9) atom. In the second K site, K(2) is bonded in a 10-coordinate geometry to one H(2), one H(3), one O(1), one O(10), one O(11), one O(13), one O(4), one O(5), one O(7), and one O(8) atom. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent S(2)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra. There are eight inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(6) atom. In the second H site, H(2) is bonded in a single-bond geometry to one K(2) and one O(7) atom. In the third H site, H(3) is bonded in a single-bond geometry to one K(2) and one O(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(3) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(4) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(11) and one O(3) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(12) and one O(4) atom. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(11), one O(12), one O(13), and one O(5) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles are 30°. In the second S site, S(2) is bonded to one O(1), one O(10), one O(8), and one O(9) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 22°. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one K(2), one Mg(1), and one S(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one H(3), and one H(4) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one K(1), one Mg(2), one H(5), and one H(7) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one K(2), one Mg(2), one H(6), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Mg(2), and one S(1) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Mg(1) and two equivalent H(1) atoms. In the seventh O site, O(7) is bonded in a distorted water-like geometry to two equivalent K(2), one Mg(1), and two equivalent H(2) atoms. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(2) and one S(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one K(1) and one S(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one K(1), one K(2), and one S(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one K(2), one H(7), and one S(1) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one K(1), one H(8), and one S(1) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one S(1) atom.
K2MgH8(SO6)2 crystallizes in the monoclinic C2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(13), one O(3), one O(5), and one O(9) atom. The K(1)-O(10) bond length is 2.77 Å. The K(1)-O(12) bond length is 2.73 Å. The K(1)-O(13) bond length is 2.81 Å. The K(1)-O(3) bond length is 2.92 Å. The K(1)-O(5) bond length is 3.00 Å. The K(1)-O(9) bond length is 2.92 Å. In the second K site, K(2) is bonded in a 10-coordinate geometry to one H(2), one H(3), one O(1), one O(10), one O(11), one O(13), one O(4), one O(5), one O(7), and one O(8) atom. The K(2)-H(2) bond length is 3.04 Å. The K(2)-H(3) bond length is 2.94 Å. The K(2)-O(1) bond length is 3.18 Å. The K(2)-O(10) bond length is 2.79 Å. The K(2)-O(11) bond length is 2.73 Å. The K(2)-O(13) bond length is 2.97 Å. The K(2)-O(4) bond length is 2.90 Å. The K(2)-O(5) bond length is 3.00 Å. The K(2)-O(7) bond length is 3.06 Å. The K(2)-O(8) bond length is 2.91 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent S(2)O4 tetrahedra. The Mg(1)-O(6) bond length is 2.11 Å. The Mg(1)-O(7) bond length is 2.12 Å. Both Mg(1)-O(1) bond lengths are 2.06 Å. Both Mg(1)-O(2) bond lengths are 2.09 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra. Both Mg(2)-O(3) bond lengths are 2.09 Å. Both Mg(2)-O(4) bond lengths are 2.09 Å. Both Mg(2)-O(5) bond lengths are 2.13 Å. There are eight inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(6) atom. The H(1)-O(6) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one K(2) and one O(7) atom. The H(2)-O(7) bond length is 1.00 Å. In the third H site, H(3) is bonded in a single-bond geometry to one K(2) and one O(2) atom. The H(3)-O(2) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. The H(4)-O(2) bond length is 0.98 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(3) atom. The H(5)-O(3) bond length is 1.00 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(4) atom. The H(6)-O(4) bond length is 1.00 Å. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(11) and one O(3) atom. The H(7)-O(11) bond length is 1.70 Å. The H(7)-O(3) bond length is 1.00 Å. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(12) and one O(4) atom. The H(8)-O(12) bond length is 1.71 Å. The H(8)-O(4) bond length is 0.99 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(11), one O(12), one O(13), and one O(5) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles are 30°. The S(1)-O(11) bond length is 1.49 Å. The S(1)-O(12) bond length is 1.49 Å. The S(1)-O(13) bond length is 1.49 Å. The S(1)-O(5) bond length is 1.49 Å. In the second S site, S(2) is bonded to one O(1), one O(10), one O(8), and one O(9) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 22°. The S(2)-O(1) bond length is 1.49 Å. The S(2)-O(10) bond length is 1.47 Å. The S(2)-O(8) bond length is 1.51 Å. The S(2)-O(9) bond length is 1.51 Å. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one K(2), one Mg(1), and one S(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one H(3), and one H(4) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one K(1), one Mg(2), one H(5), and one H(7) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one K(2), one Mg(2), one H(6), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Mg(2), and one S(1) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Mg(1) and two equivalent H(1) atoms. In the seventh O site, O(7) is bonded in a distorted water-like geometry to two equivalent K(2), one Mg(1), and two equivalent H(2) atoms. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(2) and one S(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one K(1) and one S(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one K(1), one K(2), and one S(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one K(2), one H(7), and one S(1) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one K(1), one H(8), and one S(1) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one S(1) atom.