Ba3(PSe4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one Se(2), two equivalent Se(8), three equivalent Se(1), and three equivalent Se(4) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Se(7), two equivalent Se(5), three equivalent Se(3), and three equivalent Se(6) atoms. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one Se(1), one Se(3), one Se(5), one Se(6), one Se(8), two equivalent Se(2), and two equivalent Se(7) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one Se(2), one Se(3), one Se(5), and one Se(6) atom. In the second P site, P(2) is bonded in a tetrahedral geometry to one Se(1), one Se(4), one Se(7), and one Se(8) atom. There are eight inequivalent Se sites. In the first Se site, Se(8) is bonded in a 4-coordinate geometry to one Ba(3), two equivalent Ba(1), and one P(2) atom. In the second Se site, Se(1) is bonded to one Ba(3), three equivalent Ba(1), and one P(2) atom to form a mixture of distorted corner and edge-sharing SeBa4P square pyramids. In the third Se site, Se(2) is bonded in a distorted see-saw-like geometry to one Ba(1), two equivalent Ba(3), and one P(1) atom. In the fourth Se site, Se(3) is bonded to one Ba(3), three equivalent Ba(2), and one P(1) atom to form a mixture of distorted corner and edge-sharing SeBa4P square pyramids. In the fifth Se site, Se(4) is bonded in a 1-coordinate geometry to three equivalent Ba(1) and one P(2) atom. In the sixth Se site, Se(5) is bonded in a 4-coordinate geometry to one Ba(3), two equivalent Ba(2), and one P(1) atom. In the seventh Se site, Se(6) is bonded in a 5-coordinate geometry to one Ba(3), three equivalent Ba(2), and one P(1) atom. In the eighth Se site, Se(7) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(3), and one P(2) atom.
Ba3(PSe4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one Se(2), two equivalent Se(8), three equivalent Se(1), and three equivalent Se(4) atoms. The Ba(1)-Se(2) bond length is 3.39 Å. There is one shorter (3.34 Å) and one longer (3.85 Å) Ba(1)-Se(8) bond length. There are a spread of Ba(1)-Se(1) bond distances ranging from 3.54-3.56 Å. There are a spread of Ba(1)-Se(4) bond distances ranging from 3.38-3.73 Å. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Se(7), two equivalent Se(5), three equivalent Se(3), and three equivalent Se(6) atoms. The Ba(2)-Se(7) bond length is 3.40 Å. There is one shorter (3.41 Å) and one longer (3.82 Å) Ba(2)-Se(5) bond length. There are two shorter (3.45 Å) and one longer (3.54 Å) Ba(2)-Se(3) bond length. There are a spread of Ba(2)-Se(6) bond distances ranging from 3.44-3.80 Å. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one Se(1), one Se(3), one Se(5), one Se(6), one Se(8), two equivalent Se(2), and two equivalent Se(7) atoms. The Ba(3)-Se(1) bond length is 3.45 Å. The Ba(3)-Se(3) bond length is 3.57 Å. The Ba(3)-Se(5) bond length is 3.44 Å. The Ba(3)-Se(6) bond length is 3.55 Å. The Ba(3)-Se(8) bond length is 3.38 Å. There is one shorter (3.43 Å) and one longer (3.49 Å) Ba(3)-Se(2) bond length. There is one shorter (3.46 Å) and one longer (3.71 Å) Ba(3)-Se(7) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one Se(2), one Se(3), one Se(5), and one Se(6) atom. The P(1)-Se(2) bond length is 2.22 Å. The P(1)-Se(3) bond length is 2.24 Å. The P(1)-Se(5) bond length is 2.23 Å. The P(1)-Se(6) bond length is 2.23 Å. In the second P site, P(2) is bonded in a tetrahedral geometry to one Se(1), one Se(4), one Se(7), and one Se(8) atom. The P(2)-Se(1) bond length is 2.24 Å. The P(2)-Se(4) bond length is 2.23 Å. The P(2)-Se(7) bond length is 2.23 Å. The P(2)-Se(8) bond length is 2.23 Å. There are eight inequivalent Se sites. In the first Se site, Se(8) is bonded in a 4-coordinate geometry to one Ba(3), two equivalent Ba(1), and one P(2) atom. In the second Se site, Se(1) is bonded to one Ba(3), three equivalent Ba(1), and one P(2) atom to form a mixture of distorted corner and edge-sharing SeBa4P square pyramids. In the third Se site, Se(2) is bonded in a distorted see-saw-like geometry to one Ba(1), two equivalent Ba(3), and one P(1) atom. In the fourth Se site, Se(3) is bonded to one Ba(3), three equivalent Ba(2), and one P(1) atom to form a mixture of distorted corner and edge-sharing SeBa4P square pyramids. In the fifth Se site, Se(4) is bonded in a 1-coordinate geometry to three equivalent Ba(1) and one P(2) atom. In the sixth Se site, Se(5) is bonded in a 4-coordinate geometry to one Ba(3), two equivalent Ba(2), and one P(1) atom. In the seventh Se site, Se(6) is bonded in a 5-coordinate geometry to one Ba(3), three equivalent Ba(2), and one P(1) atom. In the eighth Se site, Se(7) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(3), and one P(2) atom.