Zr3CoSe6 crystallizes in the trigonal R-3 space group. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to six equivalent Se(1) atoms to form ZrSe6 octahedra that share corners with six equivalent Co(1)Se6 octahedra and edges with six equivalent Zr(2)Se6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second Zr site, Zr(2) is bonded to six equivalent Se(1) atoms to form ZrSe6 octahedra that share corners with three equivalent Co(1)Se6 octahedra, edges with three equivalent Zr(1)Se6 octahedra, edges with three equivalent Zr(2)Se6 octahedra, and  a faceface with one Co(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 49°. Co(1) is bonded to six equivalent Se(1) atoms to form CoSe6 octahedra that share corners with six equivalent Zr(1)Se6 octahedra, corners with six equivalent Zr(2)Se6 octahedra, and faces with two equivalent Zr(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. Se(1) is bonded in a rectangular see-saw-like geometry to one Zr(1), two equivalent Zr(2), and one Co(1) atom.
Zr3CoSe6 crystallizes in the trigonal R-3 space group. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to six equivalent Se(1) atoms to form ZrSe6 octahedra that share corners with six equivalent Co(1)Se6 octahedra and edges with six equivalent Zr(2)Se6 octahedra. The corner-sharing octahedral tilt angles are 48°. All Zr(1)-Se(1) bond lengths are 2.72 Å. In the second Zr site, Zr(2) is bonded to six equivalent Se(1) atoms to form ZrSe6 octahedra that share corners with three equivalent Co(1)Se6 octahedra, edges with three equivalent Zr(1)Se6 octahedra, edges with three equivalent Zr(2)Se6 octahedra, and  a faceface with one Co(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are three shorter (2.72 Å) and three longer (2.73 Å) Zr(2)-Se(1) bond lengths. Co(1) is bonded to six equivalent Se(1) atoms to form CoSe6 octahedra that share corners with six equivalent Zr(1)Se6 octahedra, corners with six equivalent Zr(2)Se6 octahedra, and faces with two equivalent Zr(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. All Co(1)-Se(1) bond lengths are 2.56 Å. Se(1) is bonded in a rectangular see-saw-like geometry to one Zr(1), two equivalent Zr(2), and one Co(1) atom.