KSe2O crystallizes in the monoclinic Pc space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 2-coordinate geometry to one Se(4), two equivalent Se(3), one O(1), and one O(2) atom. In the second K site, K(2) is bonded in a 3-coordinate geometry to two equivalent Se(3), two equivalent Se(4), one O(1), and two equivalent O(2) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a single-bond geometry to one Se(3) and one O(1) atom. In the second Se site, Se(2) is bonded in a single-bond geometry to one Se(4) and one O(2) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent K(2), and one Se(1) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(2), and one Se(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one K(1), one K(2), and one Se(1) atom. In the second O site, O(2) is bonded to one K(1), two equivalent K(2), and one Se(2) atom to form corner-sharing OK3Se tetrahedra.
KSe2O crystallizes in the monoclinic Pc space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 2-coordinate geometry to one Se(4), two equivalent Se(3), one O(1), and one O(2) atom. The K(1)-Se(4) bond length is 3.32 Å. There is one shorter (3.37 Å) and one longer (3.71 Å) K(1)-Se(3) bond length. The K(1)-O(1) bond length is 2.72 Å. The K(1)-O(2) bond length is 2.95 Å. In the second K site, K(2) is bonded in a 3-coordinate geometry to two equivalent Se(3), two equivalent Se(4), one O(1), and two equivalent O(2) atoms. There is one shorter (3.64 Å) and one longer (3.74 Å) K(2)-Se(3) bond length. There is one shorter (3.45 Å) and one longer (3.75 Å) K(2)-Se(4) bond length. The K(2)-O(1) bond length is 2.78 Å. There is one shorter (2.85 Å) and one longer (2.96 Å) K(2)-O(2) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a single-bond geometry to one Se(3) and one O(1) atom. The Se(1)-Se(3) bond length is 2.34 Å. The Se(1)-O(1) bond length is 1.73 Å. In the second Se site, Se(2) is bonded in a single-bond geometry to one Se(4) and one O(2) atom. The Se(2)-Se(4) bond length is 2.33 Å. The Se(2)-O(2) bond length is 1.73 Å. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent K(2), and one Se(1) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(2), and one Se(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one K(1), one K(2), and one Se(1) atom. In the second O site, O(2) is bonded to one K(1), two equivalent K(2), and one Se(2) atom to form corner-sharing OK3Se tetrahedra.