RbWP2O8 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(6), one O(7), two equivalent O(1), and three equivalent O(8) atoms. W(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 WO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent W(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-42°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent W(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-38°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to one W(1) and one P(1) atom. In the second O site, O(6) is bonded in a 2-coordinate geometry to one Rb(1), one W(1), and one P(1) atom. In the third O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one P(1), and one P(2) atom. In the fourth O site, O(8) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one P(2) atom. In the fifth O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one W(1) atom. In the sixth O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), one W(1), and one P(2) atom. In the seventh O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one W(1), and one P(2) atom. In the eighth O site, O(4) is bonded in a bent 150 degrees geometry to one W(1) and one P(1) atom.
RbWP2O8 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(6), one O(7), two equivalent O(1), and three equivalent O(8) atoms. The Rb(1)-O(2) bond length is 2.99 Å. The Rb(1)-O(3) bond length is 3.30 Å. The Rb(1)-O(6) bond length is 3.22 Å. The Rb(1)-O(7) bond length is 3.03 Å. There is one shorter (2.91 Å) and one longer (3.22 Å) Rb(1)-O(1) bond length. There are a spread of Rb(1)-O(8) bond distances ranging from 2.79-3.12 Å. W(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 WO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. The W(1)-O(1) bond length is 1.72 Å. The W(1)-O(2) bond length is 2.01 Å. The W(1)-O(3) bond length is 2.02 Å. The W(1)-O(4) bond length is 2.01 Å. The W(1)-O(5) bond length is 2.03 Å. The W(1)-O(6) bond length is 2.15 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent W(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-42°. The P(1)-O(4) bond length is 1.51 Å. The P(1)-O(5) bond length is 1.52 Å. The P(1)-O(6) bond length is 1.50 Å. The P(1)-O(7) bond length is 1.60 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent W(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-38°. The P(2)-O(2) bond length is 1.53 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(7) bond length is 1.62 Å. The P(2)-O(8) bond length is 1.48 Å. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to one W(1) and one P(1) atom. In the second O site, O(6) is bonded in a 2-coordinate geometry to one Rb(1), one W(1), and one P(1) atom. In the third O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one P(1), and one P(2) atom. In the fourth O site, O(8) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one P(2) atom. In the fifth O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one W(1) atom. In the sixth O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), one W(1), and one P(2) atom. In the seventh O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one W(1), and one P(2) atom. In the eighth O site, O(4) is bonded in a bent 150 degrees geometry to one W(1) and one P(1) atom.