(Ce(SeO4)2)4O2 crystallizes in the monoclinic Cc space group. The structure consists of four water atoms inside a Ce(SeO4)2 framework. In the Ce(SeO4)2 framework, there are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(12), one O(13), one O(15), one O(4), one O(7), and one O(8) atom. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one O(11), one O(14), one O(16), one O(2), one O(3), one O(5), one O(6), and one O(9) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Se site, Se(2) is bonded in a tetrahedral geometry to one O(5), one O(6), one O(7), and one O(8) atom. In the third Se site, Se(3) is bonded in a tetrahedral geometry to one O(10), one O(11), one O(12), and one O(9) atom. In the fourth Se site, Se(4) is bonded in a tetrahedral geometry to one O(13), one O(14), one O(15), and one O(16) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ce(1) and one Se(1) atom. In the second O site, O(2) is bonded in a linear geometry to one Ce(2) and one Se(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Ce(2) and one Se(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ce(1) and one Se(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ce(2) and one Se(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ce(2) and one Se(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ce(1) and one Se(2) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Ce(2) and one Se(3) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ce(2) and one Se(3) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(3) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(4) atom. In the fourteenth O site, O(14) is bonded in a bent 120 degrees geometry to one Ce(2) and one Se(4) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Ce(1) and one Se(4) atom. In the sixteenth O site, O(16) is bonded in a distorted bent 150 degrees geometry to one Ce(2) and one Se(4) atom.
(Ce(SeO4)2)4O2 crystallizes in the monoclinic Cc space group. The structure consists of four water atoms inside a Ce(SeO4)2 framework. In the Ce(SeO4)2 framework, there are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(12), one O(13), one O(15), one O(4), one O(7), and one O(8) atom. The Ce(1)-O(1) bond length is 2.43 Å. The Ce(1)-O(10) bond length is 2.42 Å. The Ce(1)-O(12) bond length is 2.38 Å. The Ce(1)-O(13) bond length is 2.47 Å. The Ce(1)-O(15) bond length is 2.32 Å. The Ce(1)-O(4) bond length is 2.31 Å. The Ce(1)-O(7) bond length is 2.33 Å. The Ce(1)-O(8) bond length is 2.43 Å. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one O(11), one O(14), one O(16), one O(2), one O(3), one O(5), one O(6), and one O(9) atom. The Ce(2)-O(11) bond length is 2.31 Å. The Ce(2)-O(14) bond length is 2.41 Å. The Ce(2)-O(16) bond length is 2.34 Å. The Ce(2)-O(2) bond length is 2.33 Å. The Ce(2)-O(3) bond length is 2.40 Å. The Ce(2)-O(5) bond length is 2.47 Å. The Ce(2)-O(6) bond length is 2.30 Å. The Ce(2)-O(9) bond length is 2.47 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Se(1)-O(1) bond length is 1.65 Å. The Se(1)-O(2) bond length is 1.68 Å. The Se(1)-O(3) bond length is 1.67 Å. The Se(1)-O(4) bond length is 1.68 Å. In the second Se site, Se(2) is bonded in a tetrahedral geometry to one O(5), one O(6), one O(7), and one O(8) atom. The Se(2)-O(5) bond length is 1.66 Å. The Se(2)-O(6) bond length is 1.68 Å. The Se(2)-O(7) bond length is 1.67 Å. The Se(2)-O(8) bond length is 1.67 Å. In the third Se site, Se(3) is bonded in a tetrahedral geometry to one O(10), one O(11), one O(12), and one O(9) atom. The Se(3)-O(10) bond length is 1.67 Å. The Se(3)-O(11) bond length is 1.67 Å. The Se(3)-O(12) bond length is 1.67 Å. The Se(3)-O(9) bond length is 1.67 Å. In the fourth Se site, Se(4) is bonded in a tetrahedral geometry to one O(13), one O(14), one O(15), and one O(16) atom. The Se(4)-O(13) bond length is 1.65 Å. The Se(4)-O(14) bond length is 1.67 Å. The Se(4)-O(15) bond length is 1.68 Å. The Se(4)-O(16) bond length is 1.69 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ce(1) and one Se(1) atom. In the second O site, O(2) is bonded in a linear geometry to one Ce(2) and one Se(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Ce(2) and one Se(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ce(1) and one Se(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ce(2) and one Se(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ce(2) and one Se(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ce(1) and one Se(2) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Ce(2) and one Se(3) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ce(2) and one Se(3) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(3) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one Ce(1) and one Se(4) atom. In the fourteenth O site, O(14) is bonded in a bent 120 degrees geometry to one Ce(2) and one Se(4) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Ce(1) and one Se(4) atom. In the sixteenth O site, O(16) is bonded in a distorted bent 150 degrees geometry to one Ce(2) and one Se(4) atom.