K2Se3 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent Se(1) and six equivalent Se(2) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Se(1) and six equivalent Se(2) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), and two equivalent Se(2) atoms. In the second Se site, Se(2) is bonded to three equivalent K(1), three equivalent K(2), and one Se(1) atom to form a mixture of distorted face, corner, and edge-sharing SeK6Se pentagonal bipyramids.
K2Se3 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent Se(1) and six equivalent Se(2) atoms. There is one shorter (3.25 Å) and one longer (3.62 Å) K(1)-Se(1) bond length. There are a spread of K(1)-Se(2) bond distances ranging from 3.36-3.48 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Se(1) and six equivalent Se(2) atoms. The K(2)-Se(1) bond length is 3.35 Å. There are a spread of K(2)-Se(2) bond distances ranging from 3.41-3.47 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), and two equivalent Se(2) atoms. Both Se(1)-Se(2) bond lengths are 2.39 Å. In the second Se site, Se(2) is bonded to three equivalent K(1), three equivalent K(2), and one Se(1) atom to form a mixture of distorted face, corner, and edge-sharing SeK6Se pentagonal bipyramids.