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 6-coordinate geometry to one O(1), one O(2), 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 a distorted 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 4-coordinate geometry to two equivalent Rb(1) and two equivalent O(4) 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 Np(1), one O(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 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(5) atoms. The Rb(1)-O(1) bond length is 3.19 Å. The Rb(1)-O(2) bond length is 2.78 Å. There is one shorter (2.80 Å) and one longer (2.94 Å) Rb(1)-O(3) bond length. Both Rb(1)-O(5) bond lengths are 3.00 Å. 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 3.00 Å. Both Rb(2)-O(5) bond lengths are 3.08 Å. There are two shorter (3.07 Å) and two longer (3.34 Å) Rb(2)-O(2) bond lengths. Np(1) is bonded in a distorted 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 1.89 Å. Both Np(1)-O(4) bond lengths are 2.55 Å. Both Np(1)-O(5) bond lengths are 1.89 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Rb(1) and two equivalent O(4) atoms. Both O(1)-O(4) bond lengths are 1.66 Å. 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 1.34 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 Np(1), one O(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.