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TbS2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Tb4+ is bonded in a 12-coordinate geometry to twelve equivalent S2- atoms. All Tb–S bond lengths are 3.24 Å. S2- is bonded to six equivalent Tb4+ and six equivalent S2- atoms to form a mixture of corner, edge, and face-sharing STb6S6 cuboctahedra. All S–S bond lengths are 2.76 Å.
Ca(TbS2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are four shorter (2.82 Å) and four longer (3.05 Å) Ca–S bond lengths. Tb3+ is bonded to eight equivalent S2- atoms to form a mixture of distorted corner, edge, and face-sharing TbS8 hexagonal bipyramids. There are a spread of Tb–S bond distances ranging from 2.77–3.02 Å. S2- is bonded to two equivalent Ca2+ and four equivalent Tb3+ atoms to form a mixture of distorted corner, edge, and face-sharing SCa2Tb4 octahedra. The corner-sharing octahedra tilt angles range from 17–50°.
Sr(TbS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Sr–S bond distances ranging from 3.10–3.32 Å. There are two inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing TbS6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Tb–S bond distances ranging from 2.73–2.79 Å. In the second Tb3+ site, Tb3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing TbS6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Tb–S bond distances ranging from 2.70–2.80 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Tb3+ atoms. In the second S2- site, S2- is bonded to two equivalent Sr2+ and three equivalent Tb3+ atoms to form distorted edge-sharing SSr2Tb3 square pyramids. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Tb3+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three equivalent Tb3+ atoms.