Rb3NpO9 crystallizes in the monoclinic C2/c space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(2), one O(4), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to two equivalent O(3), two equivalent O(5), and four equivalent O(2) atoms. Np(1) is bonded in an octahedral geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to four equivalent Rb(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(1), two equivalent Rb(2), and one O(4) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Np(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Rb(1), one Np(1), and one O(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Np(1) atom.
Rb3NpO9 crystallizes in the monoclinic C2/c space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(2), one O(4), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. The Rb(1)-O(2) bond length is 2.89 Å. The Rb(1)-O(4) bond length is 2.98 Å. There is one shorter (2.89 Å) and one longer (3.12 Å) Rb(1)-O(1) bond length. There is one shorter (2.84 Å) and one longer (3.01 Å) Rb(1)-O(3) bond length. There is one shorter (3.07 Å) and one longer (3.15 Å) Rb(1)-O(5) bond length. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to two equivalent O(3), two equivalent O(5), and four equivalent O(2) atoms. Both Rb(2)-O(3) bond lengths are 3.13 Å. Both Rb(2)-O(5) bond lengths are 3.05 Å. There are two shorter (3.00 Å) and two longer (3.22 Å) Rb(2)-O(2) bond lengths. Np(1) is bonded in an octahedral geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Both Np(1)-O(3) bond lengths are 1.90 Å. Both Np(1)-O(4) bond lengths are 2.49 Å. Both Np(1)-O(5) bond lengths are 1.88 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to four equivalent Rb(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(1), two equivalent Rb(2), and one O(4) atom. The O(2)-O(4) bond length is 1.30 Å. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Np(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Rb(1), one Np(1), and one O(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Np(1) atom.