Rb4Li(Se2O7)2 crystallizes in the triclinic P-1 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(3), two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), one O(6), and two equivalent O(3) atoms. Li(1) is bonded in a square co-planar geometry to two equivalent O(6) and two equivalent O(7) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form corner-sharing SeO4 tetrahedra. In the second Se site, Se(2) is bonded to one O(2), one O(4), one O(6), and one O(7) atom to form distorted corner-sharing SeO4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Se(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one Se(1) atom. In the sixth O site, O(6) is bonded in a distorted L-shaped geometry to one Rb(2), one Li(1), and one Se(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(1), one Se(1), and one Se(2) atom.
Rb4Li(Se2O7)2 crystallizes in the triclinic P-1 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(3), two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. The Rb(1)-O(2) bond length is 3.04 Å. The Rb(1)-O(3) bond length is 3.12 Å. There is one shorter (3.08 Å) and one longer (3.12 Å) Rb(1)-O(1) bond length. There is one shorter (2.90 Å) and one longer (3.03 Å) Rb(1)-O(4) bond length. There is one shorter (3.21 Å) and one longer (3.50 Å) Rb(1)-O(5) bond length. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), one O(6), and two equivalent O(3) atoms. The Rb(2)-O(1) bond length is 2.98 Å. The Rb(2)-O(2) bond length is 3.11 Å. The Rb(2)-O(4) bond length is 3.10 Å. The Rb(2)-O(6) bond length is 3.11 Å. There is one shorter (2.92 Å) and one longer (2.97 Å) Rb(2)-O(3) bond length. Li(1) is bonded in a square co-planar geometry to two equivalent O(6) and two equivalent O(7) atoms. Both Li(1)-O(6) bond lengths are 2.10 Å. Both Li(1)-O(7) bond lengths are 2.05 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form corner-sharing SeO4 tetrahedra. The Se(1)-O(1) bond length is 1.67 Å. The Se(1)-O(3) bond length is 1.66 Å. The Se(1)-O(5) bond length is 1.65 Å. The Se(1)-O(7) bond length is 1.78 Å. In the second Se site, Se(2) is bonded to one O(2), one O(4), one O(6), and one O(7) atom to form distorted corner-sharing SeO4 tetrahedra. The Se(2)-O(2) bond length is 1.67 Å. The Se(2)-O(4) bond length is 1.68 Å. The Se(2)-O(6) bond length is 1.68 Å. The Se(2)-O(7) bond length is 2.18 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Se(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one Se(1) atom. In the sixth O site, O(6) is bonded in a distorted L-shaped geometry to one Rb(2), one Li(1), and one Se(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(1), one Se(1), and one Se(2) atom.