Y4N2Se3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to three equivalent N(1), one Se(1), and two equivalent Se(2) atoms. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one N(1), two equivalent Se(1), and three equivalent Se(2) atoms. N(1) is bonded to one Y(2) and three equivalent Y(1) atoms to form NY4 tetrahedra that share  a cornercorner with one Se(1)Y6 octahedra, corners with seven equivalent Se(2)Y5 square pyramids, corners with two equivalent N(1)Y4 tetrahedra, edges with two equivalent Se(1)Y6 octahedra,  an edgeedge with one Se(2)Y5 square pyramid, and edges with two equivalent N(1)Y4 tetrahedra. The corner-sharing octahedral tilt angles are 26°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form SeY6 octahedra that share corners with four equivalent Se(2)Y5 square pyramids, corners with two equivalent N(1)Y4 tetrahedra, edges with two equivalent Se(1)Y6 octahedra, edges with six equivalent Se(2)Y5 square pyramids, and edges with four equivalent N(1)Y4 tetrahedra. In the second Se site, Se(2) is bonded to two equivalent Y(1) and three equivalent Y(2) atoms to form SeY5 square pyramids that share corners with two equivalent Se(1)Y6 octahedra, corners with seven equivalent N(1)Y4 tetrahedra, edges with three equivalent Se(1)Y6 octahedra, edges with four equivalent Se(2)Y5 square pyramids, and  an edgeedge with one N(1)Y4 tetrahedra. The corner-sharing octahedral tilt angles are 13°.
Y4N2Se3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to three equivalent N(1), one Se(1), and two equivalent Se(2) atoms. There is one shorter (2.22 Å) and two longer (2.35 Å) Y(1)-N(1) bond lengths. The Y(1)-Se(1) bond length is 2.97 Å. Both Y(1)-Se(2) bond lengths are 3.04 Å. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one N(1), two equivalent Se(1), and three equivalent Se(2) atoms. The Y(2)-N(1) bond length is 2.14 Å. Both Y(2)-Se(1) bond lengths are 2.90 Å. There are two shorter (2.83 Å) and one longer (3.20 Å) Y(2)-Se(2) bond length. N(1) is bonded to one Y(2) and three equivalent Y(1) atoms to form NY4 tetrahedra that share  a cornercorner with one Se(1)Y6 octahedra, corners with seven equivalent Se(2)Y5 square pyramids, corners with two equivalent N(1)Y4 tetrahedra, edges with two equivalent Se(1)Y6 octahedra,  an edgeedge with one Se(2)Y5 square pyramid, and edges with two equivalent N(1)Y4 tetrahedra. The corner-sharing octahedral tilt angles are 26°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form SeY6 octahedra that share corners with four equivalent Se(2)Y5 square pyramids, corners with two equivalent N(1)Y4 tetrahedra, edges with two equivalent Se(1)Y6 octahedra, edges with six equivalent Se(2)Y5 square pyramids, and edges with four equivalent N(1)Y4 tetrahedra. In the second Se site, Se(2) is bonded to two equivalent Y(1) and three equivalent Y(2) atoms to form SeY5 square pyramids that share corners with two equivalent Se(1)Y6 octahedra, corners with seven equivalent N(1)Y4 tetrahedra, edges with three equivalent Se(1)Y6 octahedra, edges with four equivalent Se(2)Y5 square pyramids, and  an edgeedge with one N(1)Y4 tetrahedra. The corner-sharing octahedral tilt angles are 13°.