Rb4Ca(Se2O7)2 crystallizes in the triclinic P1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(4), one O(5), one O(6), and one O(8) atom. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom. In the third Rb site, Rb(3) is bonded in a 5-coordinate geometry to one O(12), one O(2), one O(3), one O(6), and one O(7) atom. In the fourth Rb site, Rb(4) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(14), one O(2), one O(5), one O(7), and one O(8) atom. Ca(1) is bonded in a 5-coordinate geometry to one O(13), one O(14), one O(3), one O(8), and one O(9) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(13), one O(5), and one O(9) atom to form corner-sharing SeO4 tetrahedra. In the second Se site, Se(2) is bonded to one O(10), one O(13), one O(2), and one O(6) atom to form corner-sharing SeO4 tetrahedra. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one O(11), one O(3), and one O(7) atom. In the fourth Se site, Se(4) is bonded in a tetrahedral geometry to one O(12), one O(14), one O(4), and one O(8) atom. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(4), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(3), one Rb(4), and one Se(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(2), one Rb(3), one Ca(1), and one Se(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Se(4) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted tetrahedral geometry to one Rb(2), one Rb(3), one Rb(4), and one Se(3) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(4), one Ca(1), and one Se(4) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Ca(1) and one Se(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Rb(1), one Rb(2), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Rb(1), one Rb(3), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Ca(1), one Se(1), and one Se(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Rb(4), one Ca(1), and one Se(4) atom.
Rb4Ca(Se2O7)2 crystallizes in the triclinic P1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(4), one O(5), one O(6), and one O(8) atom. The Rb(1)-O(1) bond length is 3.47 Å. The Rb(1)-O(10) bond length is 3.01 Å. The Rb(1)-O(11) bond length is 2.76 Å. The Rb(1)-O(12) bond length is 3.08 Å. The Rb(1)-O(4) bond length is 2.94 Å. The Rb(1)-O(5) bond length is 3.14 Å. The Rb(1)-O(6) bond length is 3.14 Å. The Rb(1)-O(8) bond length is 3.48 Å. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom. The Rb(2)-O(10) bond length is 2.91 Å. The Rb(2)-O(11) bond length is 3.45 Å. The Rb(2)-O(2) bond length is 3.34 Å. The Rb(2)-O(3) bond length is 3.10 Å. The Rb(2)-O(4) bond length is 3.20 Å. The Rb(2)-O(5) bond length is 3.41 Å. The Rb(2)-O(6) bond length is 3.30 Å. The Rb(2)-O(7) bond length is 2.87 Å. In the third Rb site, Rb(3) is bonded in a 5-coordinate geometry to one O(12), one O(2), one O(3), one O(6), and one O(7) atom. The Rb(3)-O(12) bond length is 2.95 Å. The Rb(3)-O(2) bond length is 3.16 Å. The Rb(3)-O(3) bond length is 3.20 Å. The Rb(3)-O(6) bond length is 2.97 Å. The Rb(3)-O(7) bond length is 2.82 Å. In the fourth Rb site, Rb(4) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(14), one O(2), one O(5), one O(7), and one O(8) atom. The Rb(4)-O(1) bond length is 2.91 Å. The Rb(4)-O(11) bond length is 3.07 Å. The Rb(4)-O(14) bond length is 3.11 Å. The Rb(4)-O(2) bond length is 3.06 Å. The Rb(4)-O(5) bond length is 2.82 Å. The Rb(4)-O(7) bond length is 3.01 Å. The Rb(4)-O(8) bond length is 3.10 Å. Ca(1) is bonded in a 5-coordinate geometry to one O(13), one O(14), one O(3), one O(8), and one O(9) atom. The Ca(1)-O(13) bond length is 2.77 Å. The Ca(1)-O(14) bond length is 2.32 Å. The Ca(1)-O(3) bond length is 2.20 Å. The Ca(1)-O(8) bond length is 2.32 Å. The Ca(1)-O(9) bond length is 2.37 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(13), one O(5), and one O(9) atom to form corner-sharing SeO4 tetrahedra. The Se(1)-O(1) bond length is 1.64 Å. The Se(1)-O(13) bond length is 1.88 Å. The Se(1)-O(5) bond length is 1.63 Å. The Se(1)-O(9) bond length is 1.67 Å. In the second Se site, Se(2) is bonded to one O(10), one O(13), one O(2), and one O(6) atom to form corner-sharing SeO4 tetrahedra. The Se(2)-O(10) bond length is 1.64 Å. The Se(2)-O(13) bond length is 1.88 Å. The Se(2)-O(2) bond length is 1.65 Å. The Se(2)-O(6) bond length is 1.65 Å. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one O(11), one O(3), and one O(7) atom. The Se(3)-O(11) bond length is 1.70 Å. The Se(3)-O(3) bond length is 1.77 Å. The Se(3)-O(7) bond length is 1.70 Å. In the fourth Se site, Se(4) is bonded in a tetrahedral geometry to one O(12), one O(14), one O(4), and one O(8) atom. The Se(4)-O(12) bond length is 1.66 Å. The Se(4)-O(14) bond length is 1.70 Å. The Se(4)-O(4) bond length is 1.66 Å. The Se(4)-O(8) bond length is 1.72 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(4), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(3), one Rb(4), and one Se(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(2), one Rb(3), one Ca(1), and one Se(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Se(4) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted tetrahedral geometry to one Rb(2), one Rb(3), one Rb(4), and one Se(3) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(4), one Ca(1), and one Se(4) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Ca(1) and one Se(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Rb(1), one Rb(2), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Rb(1), one Rb(3), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Ca(1), one Se(1), and one Se(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Rb(4), one Ca(1), and one Se(4) atom.