Na2ZrSe3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NaSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with four equivalent Na(3)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with four equivalent Na(3)Se6 octahedra, and edges with six equivalent Zr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 9-10°. In the second Na site, Na(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with four equivalent Zr(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with four equivalent Zr(1)Se6 octahedra, and edges with six equivalent Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. In the third Na site, Na(3) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with four equivalent Zr(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and edges with four equivalent Zr(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 9°. Zr(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form ZrSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with four equivalent Na(3)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, edges with three equivalent Zr(1)Se6 octahedra, and edges with four equivalent Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 8-9°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), one Na(2), two equivalent Na(3), and two equivalent Zr(1) atoms to form a mixture of corner and edge-sharing SeNa4Zr2 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second Se site, Se(2) is bonded to one Na(1), one Na(2), two equivalent Na(3), and two equivalent Zr(1) atoms to form a mixture of corner and edge-sharing SeNa4Zr2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°.
Na2ZrSe3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NaSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with four equivalent Na(3)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with four equivalent Na(3)Se6 octahedra, and edges with six equivalent Zr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 9-10°. Both Na(1)-Se(2) bond lengths are 2.93 Å. All Na(1)-Se(1) bond lengths are 2.94 Å. In the second Na site, Na(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with four equivalent Zr(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with four equivalent Zr(1)Se6 octahedra, and edges with six equivalent Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. Both Na(2)-Se(2) bond lengths are 2.86 Å. All Na(2)-Se(1) bond lengths are 3.06 Å. In the third Na site, Na(3) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with four equivalent Zr(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and edges with four equivalent Zr(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 9°. Both Na(3)-Se(2) bond lengths are 2.98 Å. There are two shorter (2.91 Å) and two longer (3.08 Å) Na(3)-Se(1) bond lengths. Zr(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form ZrSe6 octahedra that share corners with two equivalent Na(2)Se6 octahedra, corners with four equivalent Na(3)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, edges with three equivalent Zr(1)Se6 octahedra, and edges with four equivalent Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 8-9°. Both Zr(1)-Se(2) bond lengths are 2.73 Å. There are two shorter (2.70 Å) and two longer (2.71 Å) Zr(1)-Se(1) bond lengths. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), one Na(2), two equivalent Na(3), and two equivalent Zr(1) atoms to form a mixture of corner and edge-sharing SeNa4Zr2 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second Se site, Se(2) is bonded to one Na(1), one Na(2), two equivalent Na(3), and two equivalent Zr(1) atoms to form a mixture of corner and edge-sharing SeNa4Zr2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°.