Cs6MgNp2(H8O9)2 crystallizes in the monoclinic C2 space group. There are four inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 7-coordinate geometry to one H(4), one H(8), one O(2), one O(3), one O(4), one O(7), and one O(8) atom. In the second Cs site, Cs(2) is bonded in a 12-coordinate geometry to one H(1), one H(3), one H(6), one H(7), one O(1), one O(2), one O(3), one O(4), one O(5), one O(7), one O(8), and one O(9) atom. In the third Cs site, Cs(3) is bonded in a 10-coordinate geometry to two equivalent H(3), two equivalent H(6), two equivalent O(2), two equivalent O(3), and two equivalent O(7) atoms. In the fourth Cs site, Cs(4) is bonded in a 8-coordinate geometry to two equivalent H(4), two equivalent O(1), two equivalent O(4), and two equivalent O(7) atoms. Mg(1) is bonded to two equivalent O(6) and two equivalent O(8) atoms to form MgO4 tetrahedra that share corners with two equivalent Np(1)O6 octahedra. The corner-sharing octahedral tilt angles are 71°. Np(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted NpO6 octahedra that share  a cornercorner with one Mg(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 Cs(2) and one O(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. In the third H site, H(3) is bonded in a single-bond geometry to one Cs(2), one Cs(3), and one O(7) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one Cs(1), one Cs(4), and one O(1) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(7) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one Cs(2), one Cs(3), and one O(8) atom. In the seventh H site, H(7) is bonded in a distorted single-bond geometry to one Cs(2) and one O(9) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one Cs(1) and one O(10) atom. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(4), one Np(1), and one H(4) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(3), and one Np(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(3), and one Np(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(4), and one Np(1) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one Cs(2), one Np(1), and one H(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Mg(1), one Np(1), and one H(2) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Cs(1), one Cs(2), one Cs(3), one Cs(4), one H(3), and one H(5) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), one Mg(1), and one H(6) atom. In the ninth O site, O(9) is bonded in a water-like geometry to two equivalent Cs(2) and two equivalent H(7) atoms. In the tenth O site, O(10) is bonded in a water-like geometry to two equivalent H(8) atoms.
Cs6MgNp2(H8O9)2 crystallizes in the monoclinic C2 space group. There are four inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 7-coordinate geometry to one H(4), one H(8), one O(2), one O(3), one O(4), one O(7), and one O(8) atom. The Cs(1)-H(4) bond length is 2.87 Å. The Cs(1)-H(8) bond length is 2.86 Å. The Cs(1)-O(2) bond length is 3.17 Å. The Cs(1)-O(3) bond length is 3.03 Å. The Cs(1)-O(4) bond length is 3.40 Å. The Cs(1)-O(7) bond length is 3.17 Å. The Cs(1)-O(8) bond length is 3.13 Å. In the second Cs site, Cs(2) is bonded in a 12-coordinate geometry to one H(1), one H(3), one H(6), one H(7), one O(1), one O(2), one O(3), one O(4), one O(5), one O(7), one O(8), and one O(9) atom. The Cs(2)-H(1) bond length is 3.36 Å. The Cs(2)-H(3) bond length is 3.12 Å. The Cs(2)-H(6) bond length is 3.33 Å. The Cs(2)-H(7) bond length is 3.04 Å. The Cs(2)-O(1) bond length is 3.13 Å. The Cs(2)-O(2) bond length is 3.19 Å. The Cs(2)-O(3) bond length is 3.36 Å. The Cs(2)-O(4) bond length is 3.13 Å. The Cs(2)-O(5) bond length is 3.33 Å. The Cs(2)-O(7) bond length is 3.21 Å. The Cs(2)-O(8) bond length is 3.22 Å. The Cs(2)-O(9) bond length is 3.35 Å. In the third Cs site, Cs(3) is bonded in a 10-coordinate geometry to two equivalent H(3), two equivalent H(6), two equivalent O(2), two equivalent O(3), and two equivalent O(7) atoms. Both Cs(3)-H(3) bond lengths are 2.98 Å. Both Cs(3)-H(6) bond lengths are 2.82 Å. Both Cs(3)-O(2) bond lengths are 3.11 Å. Both Cs(3)-O(3) bond lengths are 3.38 Å. Both Cs(3)-O(7) bond lengths are 3.18 Å. In the fourth Cs site, Cs(4) is bonded in a 8-coordinate geometry to two equivalent H(4), two equivalent O(1), two equivalent O(4), and two equivalent O(7) atoms. Both Cs(4)-H(4) bond lengths are 3.22 Å. Both Cs(4)-O(1) bond lengths are 3.33 Å. Both Cs(4)-O(4) bond lengths are 3.06 Å. Both Cs(4)-O(7) bond lengths are 3.19 Å. Mg(1) is bonded to two equivalent O(6) and two equivalent O(8) atoms to form MgO4 tetrahedra that share corners with two equivalent Np(1)O6 octahedra. The corner-sharing octahedral tilt angles are 71°. Both Mg(1)-O(6) bond lengths are 2.07 Å. Both Mg(1)-O(8) bond lengths are 1.96 Å. Np(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted NpO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra. The Np(1)-O(1) bond length is 2.23 Å. The Np(1)-O(2) bond length is 1.99 Å. The Np(1)-O(3) bond length is 1.89 Å. The Np(1)-O(4) bond length is 1.88 Å. The Np(1)-O(5) bond length is 2.39 Å. The Np(1)-O(6) bond length is 2.52 Å. There are eight inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one Cs(2) and one O(5) atom. The H(1)-O(5) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. The H(2)-O(6) bond length is 0.98 Å. In the third H site, H(3) is bonded in a single-bond geometry to one Cs(2), one Cs(3), and one O(7) atom. The H(3)-O(7) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one Cs(1), one Cs(4), and one O(1) atom. The H(4)-O(1) bond length is 0.99 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(7) atom. The H(5)-O(7) bond length is 1.00 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one Cs(2), one Cs(3), and one O(8) atom. The H(6)-O(8) bond length is 0.97 Å. In the seventh H site, H(7) is bonded in a distorted single-bond geometry to one Cs(2) and one O(9) atom. The H(7)-O(9) bond length is 1.01 Å. In the eighth H site, H(8) is bonded in a single-bond geometry to one Cs(1) and one O(10) atom. The H(8)-O(10) bond length is 1.00 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(4), one Np(1), and one H(4) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(3), and one Np(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(3), and one Np(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(4), and one Np(1) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one Cs(2), one Np(1), and one H(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Mg(1), one Np(1), and one H(2) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Cs(1), one Cs(2), one Cs(3), one Cs(4), one H(3), and one H(5) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), one Mg(1), and one H(6) atom. In the ninth O site, O(9) is bonded in a water-like geometry to two equivalent Cs(2) and two equivalent H(7) atoms. In the tenth O site, O(10) is bonded in a water-like geometry to two equivalent H(8) atoms.