Rb4Li(Se2O7)2 crystallizes in the monoclinic C2 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent 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 one O(2), one O(3), one O(5), one O(6), two equivalent O(1), and two equivalent O(4) atoms. Li(1) is bonded in a trigonal planar geometry to one O(8) and two equivalent O(1) 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(8) atom to form corner-sharing SeO4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(2), one Li(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(1), two equivalent Rb(2), and one Se(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 Se(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Rb(2) and one Se(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to two equivalent Se(1) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Li(1) and two equivalent Se(2) atoms.
Rb4Li(Se2O7)2 crystallizes in the monoclinic C2 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. The Rb(1)-O(4) bond length is 2.94 Å. There is one shorter (2.97 Å) and one longer (3.08 Å) Rb(1)-O(2) bond length. There is one shorter (2.95 Å) and one longer (3.03 Å) Rb(1)-O(3) bond length. There is one shorter (3.15 Å) and one longer (3.23 Å) Rb(1)-O(5) bond length. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(5), one O(6), two equivalent O(1), and two equivalent O(4) atoms. The Rb(2)-O(2) bond length is 3.19 Å. The Rb(2)-O(3) bond length is 2.96 Å. The Rb(2)-O(5) bond length is 3.03 Å. The Rb(2)-O(6) bond length is 3.33 Å. There is one shorter (3.14 Å) and one longer (3.20 Å) Rb(2)-O(1) bond length. There is one shorter (3.02 Å) and one longer (3.05 Å) Rb(2)-O(4) bond length. Li(1) is bonded in a trigonal planar geometry to one O(8) and two equivalent O(1) atoms. The Li(1)-O(8) bond length is 1.95 Å. Both Li(1)-O(1) bond lengths are 1.89 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 1.71 Å. The Se(1)-O(3) bond length is 1.68 Å. The Se(1)-O(5) bond length is 1.69 Å. The Se(1)-O(7) bond length is 1.94 Å. In the second Se site, Se(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form corner-sharing SeO4 tetrahedra. The Se(2)-O(2) bond length is 1.65 Å. The Se(2)-O(4) bond length is 1.65 Å. The Se(2)-O(6) bond length is 1.64 Å. The Se(2)-O(8) bond length is 1.85 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(2), one Li(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(1), two equivalent Rb(2), and one Se(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 Se(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Rb(2) and one Se(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to two equivalent Se(1) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Li(1) and two equivalent Se(2) atoms.