Ti3NiS6 crystallizes in the trigonal P-31c space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to six equivalent S(1) atoms to form TiS6 octahedra that share corners with three equivalent Ni(1)S6 octahedra, edges with three equivalent Ti(1)S6 octahedra, edges with three equivalent Ti(2)S6 octahedra, and  a faceface with one Ni(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second Ti site, Ti(2) is bonded to six equivalent S(1) atoms to form TiS6 octahedra that share corners with six equivalent Ni(1)S6 octahedra and edges with six equivalent Ti(1)S6 octahedra. The corner-sharing octahedral tilt angles are 47°. Ni(1) is bonded to six equivalent S(1) atoms to form NiS6 octahedra that share corners with six equivalent Ti(1)S6 octahedra, corners with six equivalent Ti(2)S6 octahedra, and faces with two equivalent Ti(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 47-48°. S(1) is bonded in a rectangular see-saw-like geometry to one Ti(2), two equivalent Ti(1), and one Ni(1) atom.
Ti3NiS6 crystallizes in the trigonal P-31c space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to six equivalent S(1) atoms to form TiS6 octahedra that share corners with three equivalent Ni(1)S6 octahedra, edges with three equivalent Ti(1)S6 octahedra, edges with three equivalent Ti(2)S6 octahedra, and  a faceface with one Ni(1)S6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are three shorter (2.42 Å) and three longer (2.46 Å) Ti(1)-S(1) bond lengths. In the second Ti site, Ti(2) is bonded to six equivalent S(1) atoms to form TiS6 octahedra that share corners with six equivalent Ni(1)S6 octahedra and edges with six equivalent Ti(1)S6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Ti(2)-S(1) bond lengths are 2.44 Å. Ni(1) is bonded to six equivalent S(1) atoms to form NiS6 octahedra that share corners with six equivalent Ti(1)S6 octahedra, corners with six equivalent Ti(2)S6 octahedra, and faces with two equivalent Ti(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 47-48°. All Ni(1)-S(1) bond lengths are 2.40 Å. S(1) is bonded in a rectangular see-saw-like geometry to one Ti(2), two equivalent Ti(1), and one Ni(1) atom.