Rb4NpS2O10Cl crystallizes in the monoclinic P2/c space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to one O(4), one O(5), two equivalent O(1), three equivalent O(3), and one Cl(1) atom to form distorted RbClO7 hexagonal bipyramids that share  a cornercorner with one Rb(1)ClO7 hexagonal bipyramid,  a cornercorner with one S(1)O4 tetrahedra, edges with four equivalent Rb(1)ClO7 hexagonal bipyramids, and edges with two equivalent S(1)O4 tetrahedra. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one O(1), one O(4), three equivalent O(2), and two equivalent Cl(1) atoms. Np(1) is bonded in a distorted linear geometry to two equivalent O(1) atoms. S(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SO4 tetrahedra that share  a cornercorner with one Rb(1)ClO7 hexagonal bipyramid and edges with two equivalent Rb(1)ClO7 hexagonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Np(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to three equivalent Rb(2) and one S(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one S(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Rb(1) and one S(1) atom. Cl(1) is bonded to two equivalent Rb(1) and four equivalent Rb(2) atoms to form edge-sharing ClRb6 octahedra.
Rb4NpS2O10Cl crystallizes in the monoclinic P2/c space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to one O(4), one O(5), two equivalent O(1), three equivalent O(3), and one Cl(1) atom to form distorted RbClO7 hexagonal bipyramids that share  a cornercorner with one Rb(1)ClO7 hexagonal bipyramid,  a cornercorner with one S(1)O4 tetrahedra, edges with four equivalent Rb(1)ClO7 hexagonal bipyramids, and edges with two equivalent S(1)O4 tetrahedra. The Rb(1)-O(4) bond length is 3.29 Å. The Rb(1)-O(5) bond length is 3.25 Å. There is one shorter (3.01 Å) and one longer (3.04 Å) Rb(1)-O(1) bond length. There are a spread of Rb(1)-O(3) bond distances ranging from 2.87-3.21 Å. The Rb(1)-Cl(1) bond length is 3.30 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one O(1), one O(4), three equivalent O(2), and two equivalent Cl(1) atoms. The Rb(2)-O(1) bond length is 3.02 Å. The Rb(2)-O(4) bond length is 3.12 Å. There are a spread of Rb(2)-O(2) bond distances ranging from 2.92-3.03 Å. There is one shorter (3.32 Å) and one longer (3.34 Å) Rb(2)-Cl(1) bond length. Np(1) is bonded in a distorted linear geometry to two equivalent O(1) atoms. Both Np(1)-O(1) bond lengths are 1.85 Å. S(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SO4 tetrahedra that share  a cornercorner with one Rb(1)ClO7 hexagonal bipyramid and edges with two equivalent Rb(1)ClO7 hexagonal bipyramids. The S(1)-O(2) bond length is 1.48 Å. The S(1)-O(3) bond length is 1.48 Å. The S(1)-O(4) bond length is 1.51 Å. The S(1)-O(5) bond length is 1.52 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Np(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to three equivalent Rb(2) and one S(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one S(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Rb(1) and one S(1) atom. Cl(1) is bonded to two equivalent Rb(1) and four equivalent Rb(2) atoms to form edge-sharing ClRb6 octahedra.