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Hf2S is Molybdenite-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two Hf2S sheets oriented in the (0, 0, 1) direction. Hf is bonded in a 3-coordinate geometry to three equivalent S atoms. All Hf–S bond lengths are 2.63 Å. S is bonded to six equivalent Hf atoms to form distorted edge-sharing SHf6 pentagonal pyramids.
HfS2 is trigonal omega structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one HfS2 sheet oriented in the (0, 0, 1) direction. Hf4+ is bonded to six equivalent S2- atoms to form edge-sharing HfS6 octahedra. All Hf–S bond lengths are 2.55 Å. S2- is bonded in a distorted T-shaped geometry to three equivalent Hf4+ atoms.
HfS3 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one HfS3 sheet oriented in the (0, 0, 1) direction. Hf4+ is bonded in a 8-coordinate geometry to eight S+1.33- atoms. There are a spread of Hf–S bond distances ranging from 2.59–2.73 Å. There are three inequivalent S+1.33- sites. In the first S+1.33- site, S+1.33- is bonded in a 2-coordinate geometry to two equivalent Hf4+ atoms. In the second S+1.33- site, S+1.33- is bonded to four equivalent Hf4+ atoms to form a mixture of distorted edge and corner-sharing SHf4 trigonal pyramids. In the third S+1.33- site, S+1.33- is bonded in a 2-coordinate geometry to two equivalent Hf4+ atoms.
HfS is Tungsten Carbide structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Hf is bonded to six equivalent S atoms to form a mixture of distorted corner, edge, and face-sharing HfS6 pentagonal pyramids. All Hf–S bond lengths are 2.61 Å. S is bonded to six equivalent Hf atoms to form a mixture of distorted corner, edge, and face-sharing SHf6 pentagonal pyramids.