KY(PSe3)2 is Zircon-derived structured and crystallizes in the orthorhombic P2_12_12_1 space group. K(1) is bonded in a 7-coordinate geometry to one Se(3), one Se(4), two equivalent Se(5), and three equivalent Se(2) atoms. Y(1) is bonded in a 8-coordinate geometry to one Se(3), one Se(5), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(6) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one P(2), one Se(2), one Se(5), and one Se(6) atom to form distorted PPSe3 tetrahedra that share  a cornercorner with one Se(4)KY2P tetrahedra. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one P(1), one Se(1), one Se(3), and one Se(4) atom. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted T-shaped geometry to two equivalent Y(1) and one P(2) atom. In the second Se site, Se(2) is bonded in a 4-coordinate geometry to three equivalent K(1) and one P(1) atom. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to one K(1), one Y(1), and one P(2) atom. In the fourth Se site, Se(4) is bonded to one K(1), two equivalent Y(1), and one P(2) atom to form distorted SeKY2P tetrahedra that share  a cornercorner with one P(1)PSe3 tetrahedra and corners with two equivalent Se(4)KY2P tetrahedra. In the fifth Se site, Se(5) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Y(1), and one P(1) atom. In the sixth Se site, Se(6) is bonded in a trigonal non-coplanar geometry to two equivalent Y(1) and one P(1) atom.
KY(PSe3)2 is Zircon-derived structured and crystallizes in the orthorhombic P2_12_12_1 space group. K(1) is bonded in a 7-coordinate geometry to one Se(3), one Se(4), two equivalent Se(5), and three equivalent Se(2) atoms. The K(1)-Se(3) bond length is 3.61 Å. The K(1)-Se(4) bond length is 3.79 Å. There is one shorter (3.51 Å) and one longer (3.66 Å) K(1)-Se(5) bond length. There are a spread of K(1)-Se(2) bond distances ranging from 3.46-3.64 Å. Y(1) is bonded in a 8-coordinate geometry to one Se(3), one Se(5), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(6) atoms. The Y(1)-Se(3) bond length is 3.06 Å. The Y(1)-Se(5) bond length is 3.08 Å. There is one shorter (2.98 Å) and one longer (3.00 Å) Y(1)-Se(1) bond length. There is one shorter (3.03 Å) and one longer (3.09 Å) Y(1)-Se(4) bond length. There is one shorter (2.99 Å) and one longer (3.11 Å) Y(1)-Se(6) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one P(2), one Se(2), one Se(5), and one Se(6) atom to form distorted PPSe3 tetrahedra that share  a cornercorner with one Se(4)KY2P tetrahedra. The P(1)-P(2) bond length is 2.26 Å. The P(1)-Se(2) bond length is 2.17 Å. The P(1)-Se(5) bond length is 2.18 Å. The P(1)-Se(6) bond length is 2.25 Å. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one P(1), one Se(1), one Se(3), and one Se(4) atom. The P(2)-Se(1) bond length is 2.25 Å. The P(2)-Se(3) bond length is 2.19 Å. The P(2)-Se(4) bond length is 2.24 Å. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted T-shaped geometry to two equivalent Y(1) and one P(2) atom. In the second Se site, Se(2) is bonded in a 4-coordinate geometry to three equivalent K(1) and one P(1) atom. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to one K(1), one Y(1), and one P(2) atom. In the fourth Se site, Se(4) is bonded to one K(1), two equivalent Y(1), and one P(2) atom to form distorted SeKY2P tetrahedra that share  a cornercorner with one P(1)PSe3 tetrahedra and corners with two equivalent Se(4)KY2P tetrahedra. In the fifth Se site, Se(5) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Y(1), and one P(1) atom. In the sixth Se site, Se(6) is bonded in a trigonal non-coplanar geometry to two equivalent Y(1) and one P(1) atom.