Tb2HfS5 crystallizes in the orthorhombic Pnma space group. Tb(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. Hf(1) is bonded to one S(2), one S(3), one S(4), and four equivalent S(1) atoms to form distorted edge-sharing HfS7 pentagonal bipyramids. There are four inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Tb(1) and two equivalent Hf(1) atoms to form distorted STb2Hf2 trigonal pyramids that share corners with four equivalent S(3)Tb4Hf square pyramids, corners with two equivalent S(2)Tb4Hf trigonal bipyramids, corners with two equivalent S(4)Tb4Hf trigonal bipyramids, corners with six equivalent S(1)Tb2Hf2 trigonal pyramids,  an edgeedge with one S(3)Tb4Hf square pyramid, edges with two equivalent S(2)Tb4Hf trigonal bipyramids, edges with two equivalent S(4)Tb4Hf trigonal bipyramids, and  an edgeedge with one S(1)Tb2Hf2 trigonal pyramid. In the second S site, S(2) is bonded to four equivalent Tb(1) and one Hf(1) atom to form distorted STb4Hf trigonal bipyramids that share corners with five equivalent S(3)Tb4Hf square pyramids,  a cornercorner with one S(4)Tb4Hf trigonal bipyramid, corners with four equivalent S(2)Tb4Hf trigonal bipyramids, corners with four equivalent S(1)Tb2Hf2 trigonal pyramids, edges with two equivalent S(3)Tb4Hf square pyramids, edges with four equivalent S(4)Tb4Hf trigonal bipyramids, and edges with four equivalent S(1)Tb2Hf2 trigonal pyramids. In the third S site, S(3) is bonded to four equivalent Tb(1) and one Hf(1) atom to form STb4Hf square pyramids that share corners with four equivalent S(4)Tb4Hf trigonal bipyramids, corners with five equivalent S(2)Tb4Hf trigonal bipyramids, corners with eight equivalent S(1)Tb2Hf2 trigonal pyramids, edges with two equivalent S(3)Tb4Hf square pyramids,  an edgeedge with one S(4)Tb4Hf trigonal bipyramid, edges with two equivalent S(2)Tb4Hf trigonal bipyramids, edges with two equivalent S(1)Tb2Hf2 trigonal pyramids, and  a faceface with one S(4)Tb4Hf trigonal bipyramid. In the fourth S site, S(4) is bonded to four equivalent Tb(1) and one Hf(1) atom to form distorted STb4Hf trigonal bipyramids that share corners with four equivalent S(3)Tb4Hf square pyramids,  a cornercorner with one S(2)Tb4Hf trigonal bipyramid, corners with four equivalent S(4)Tb4Hf trigonal bipyramids, corners with four equivalent S(1)Tb2Hf2 trigonal pyramids,  an edgeedge with one S(3)Tb4Hf square pyramid, edges with four equivalent S(2)Tb4Hf trigonal bipyramids, edges with four equivalent S(1)Tb2Hf2 trigonal pyramids, and  a faceface with one S(3)Tb4Hf square pyramid.
Tb2HfS5 crystallizes in the orthorhombic Pnma space group. Tb(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. There is one shorter (2.83 Å) and one longer (2.84 Å) Tb(1)-S(1) bond length. There is one shorter (2.86 Å) and one longer (2.99 Å) Tb(1)-S(2) bond length. There is one shorter (2.85 Å) and one longer (2.86 Å) Tb(1)-S(3) bond length. There is one shorter (2.82 Å) and one longer (2.86 Å) Tb(1)-S(4) bond length. Hf(1) is bonded to one S(2), one S(3), one S(4), and four equivalent S(1) atoms to form distorted edge-sharing HfS7 pentagonal bipyramids. The Hf(1)-S(2) bond length is 2.67 Å. The Hf(1)-S(3) bond length is 2.70 Å. The Hf(1)-S(4) bond length is 2.58 Å. There are two shorter (2.51 Å) and two longer (2.64 Å) Hf(1)-S(1) bond lengths. There are four inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Tb(1) and two equivalent Hf(1) atoms to form distorted STb2Hf2 trigonal pyramids that share corners with four equivalent S(3)Tb4Hf square pyramids, corners with two equivalent S(2)Tb4Hf trigonal bipyramids, corners with two equivalent S(4)Tb4Hf trigonal bipyramids, corners with six equivalent S(1)Tb2Hf2 trigonal pyramids,  an edgeedge with one S(3)Tb4Hf square pyramid, edges with two equivalent S(2)Tb4Hf trigonal bipyramids, edges with two equivalent S(4)Tb4Hf trigonal bipyramids, and  an edgeedge with one S(1)Tb2Hf2 trigonal pyramid. In the second S site, S(2) is bonded to four equivalent Tb(1) and one Hf(1) atom to form distorted STb4Hf trigonal bipyramids that share corners with five equivalent S(3)Tb4Hf square pyramids,  a cornercorner with one S(4)Tb4Hf trigonal bipyramid, corners with four equivalent S(2)Tb4Hf trigonal bipyramids, corners with four equivalent S(1)Tb2Hf2 trigonal pyramids, edges with two equivalent S(3)Tb4Hf square pyramids, edges with four equivalent S(4)Tb4Hf trigonal bipyramids, and edges with four equivalent S(1)Tb2Hf2 trigonal pyramids. In the third S site, S(3) is bonded to four equivalent Tb(1) and one Hf(1) atom to form STb4Hf square pyramids that share corners with four equivalent S(4)Tb4Hf trigonal bipyramids, corners with five equivalent S(2)Tb4Hf trigonal bipyramids, corners with eight equivalent S(1)Tb2Hf2 trigonal pyramids, edges with two equivalent S(3)Tb4Hf square pyramids,  an edgeedge with one S(4)Tb4Hf trigonal bipyramid, edges with two equivalent S(2)Tb4Hf trigonal bipyramids, edges with two equivalent S(1)Tb2Hf2 trigonal pyramids, and  a faceface with one S(4)Tb4Hf trigonal bipyramid. In the fourth S site, S(4) is bonded to four equivalent Tb(1) and one Hf(1) atom to form distorted STb4Hf trigonal bipyramids that share corners with four equivalent S(3)Tb4Hf square pyramids,  a cornercorner with one S(2)Tb4Hf trigonal bipyramid, corners with four equivalent S(4)Tb4Hf trigonal bipyramids, corners with four equivalent S(1)Tb2Hf2 trigonal pyramids,  an edgeedge with one S(3)Tb4Hf square pyramid, edges with four equivalent S(2)Tb4Hf trigonal bipyramids, edges with four equivalent S(1)Tb2Hf2 trigonal pyramids, and  a faceface with one S(3)Tb4Hf square pyramid.