Na3AsSe3 crystallizes in the cubic P2_13 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to six equivalent Se(1) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to six equivalent Se(1) atoms. In the third Na site, Na(3) is bonded to six equivalent Se(1) atoms to form distorted corner-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles are 59°. As(1) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Se(1) atoms. Se(1) is bonded to two equivalent Na(1), two equivalent Na(2), two equivalent Na(3), and one As(1) atom to form a mixture of distorted corner, edge, and face-sharing SeNa6As pentagonal bipyramids.
Na3AsSe3 crystallizes in the cubic P2_13 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to six equivalent Se(1) atoms. There are three shorter (2.96 Å) and three longer (3.12 Å) Na(1)-Se(1) bond lengths. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to six equivalent Se(1) atoms. There are three shorter (2.97 Å) and three longer (3.12 Å) Na(2)-Se(1) bond lengths. In the third Na site, Na(3) is bonded to six equivalent Se(1) atoms to form distorted corner-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are three shorter (3.09 Å) and three longer (3.26 Å) Na(3)-Se(1) bond lengths. As(1) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Se(1) atoms. All As(1)-Se(1) bond lengths are 2.41 Å. Se(1) is bonded to two equivalent Na(1), two equivalent Na(2), two equivalent Na(3), and one As(1) atom to form a mixture of distorted corner, edge, and face-sharing SeNa6As pentagonal bipyramids.