K3(SeO4)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. In the second K site, K(2) is bonded in a 10-coordinate geometry to one O(2), three equivalent O(1), three equivalent O(3), and three equivalent O(4) atoms. Se(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 1-coordinate geometry to one K(1), three equivalent K(2), and one Se(1) atom. In the second O site, O(1) is bonded in a 1-coordinate geometry to one K(1), three equivalent K(2), and one Se(1) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one K(2), two equivalent K(1), and one Se(1) atom. In the fourth O site, O(3) is bonded in a distorted single-bond geometry to one K(1), three equivalent K(2), and one Se(1) atom.
K3(SeO4)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. Both K(1)-O(1) bond lengths are 2.94 Å. Both K(1)-O(3) bond lengths are 2.92 Å. Both K(1)-O(4) bond lengths are 2.77 Å. There are two shorter (3.15 Å) and two longer (3.26 Å) K(1)-O(2) bond lengths. In the second K site, K(2) is bonded in a 10-coordinate geometry to one O(2), three equivalent O(1), three equivalent O(3), and three equivalent O(4) atoms. The K(2)-O(2) bond length is 2.94 Å. There are a spread of K(2)-O(1) bond distances ranging from 2.81-3.12 Å. There are a spread of K(2)-O(3) bond distances ranging from 2.85-3.13 Å. There are a spread of K(2)-O(4) bond distances ranging from 3.03-3.35 Å. 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 1.66 Å. The Se(1)-O(2) bond length is 1.72 Å. The Se(1)-O(3) bond length is 1.67 Å. The Se(1)-O(4) bond length is 1.67 Å. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 1-coordinate geometry to one K(1), three equivalent K(2), and one Se(1) atom. In the second O site, O(1) is bonded in a 1-coordinate geometry to one K(1), three equivalent K(2), and one Se(1) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one K(2), two equivalent K(1), and one Se(1) atom. In the fourth O site, O(3) is bonded in a distorted single-bond geometry to one K(1), three equivalent K(2), and one Se(1) atom.