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HfCo is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to eight equivalent Co atoms. All Hf–Co bond lengths are 2.73 Å. Co is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.
Hf6Co23 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to twelve Co atoms. There are a spread of Hf–Co bond distances ranging from 2.73–2.87 Å. There are four inequivalent Co sites. In the first Co site, Co is bonded in a distorted q6 geometry to three equivalent Hf and nine Co atoms. There are a spread of Co–Co bond distances ranging from 2.32–2.50 Å. In the second Co site, Co is bonded in a body-centered cubic geometry to eight equivalent Co atoms. All Co–Co bond lengths are 2.36 Å. In the third Co site, Co is bonded to four equivalent Hf and eight Co atoms to form a mixture of face and corner-sharing CoHf4Co8 cuboctahedra. All Co–Co bond lengths are 2.49 Å. In the fourth Co site, Co is bonded in a 4-coordinate geometry to three equivalent Hf and ten Co atoms. All Co–Co bond lengths are 2.73 Å.
HfCo3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf is bonded to twelve Co atoms to form HfCo12 cuboctahedra that share corners with six equivalent HfCo12 cuboctahedra, corners with twelve CoHf4Co8 cuboctahedra, edges with eighteen CoHf4Co8 cuboctahedra, faces with eight equivalent HfCo12 cuboctahedra, and faces with twelve CoHf4Co8 cuboctahedra. There are six shorter (2.67 Å) and six longer (2.69 Å) Hf–Co bond lengths. There are three inequivalent Co sites. In the first Co site, Co is bonded to four equivalent Hf and eight Co atoms to form distorted CoHf4Co8 cuboctahedra that share corners with four equivalent HfCo12 cuboctahedra, corners with fourteen CoHf4Co8 cuboctahedra, edges with six equivalent HfCo12 cuboctahedra, edges with twelve CoHf4Co8 cuboctahedra, faces with four equivalent HfCo12 cuboctahedra, and faces with sixteen CoHf4Co8 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.48–2.85 Å. In the second Co site, Co is bonded to four equivalent Hf and eight equivalent Co atoms to form distorted CoHf4Co8 cuboctahedra that share corners with four equivalent HfCo12 cuboctahedra, corners with fourteen CoHf4Co8 cuboctahedra, edges with six equivalent HfCo12 cuboctahedra, edges with twelve equivalent CoHf4Co8 cuboctahedra, faces with four equivalent HfCo12 cuboctahedra, and faces with sixteen CoHf4Co8 cuboctahedra. In the third Co site, Co is bonded to four equivalent Hf and eight equivalent Co atoms to form distorted CoHf4Co8 cuboctahedra that share corners with four equivalent HfCo12 cuboctahedra, corners with fourteen CoHf4Co8 cuboctahedra, edges with six equivalent HfCo12 cuboctahedra, edges with twelve equivalent CoHf4Co8 cuboctahedra, faces with four equivalent HfCo12 cuboctahedra, and faces with sixteen CoHf4Co8 cuboctahedra.
Co7Hf2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Hf is bonded in a 8-coordinate geometry to fourteen Co atoms. There are a spread of Hf–Co bond distances ranging from 2.73–2.87 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to four equivalent Hf and eight Co atoms to form a mixture of face, edge, and corner-sharing CoHf4Co8 cuboctahedra. There are four shorter (2.37 Å) and four longer (2.50 Å) Co–Co bond lengths. In the second Co site, Co is bonded to four equivalent Hf and eight Co atoms to form a mixture of face, edge, and corner-sharing CoHf4Co8 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.33–2.49 Å. In the third Co site, Co is bonded in a 12-coordinate geometry to four equivalent Hf and eight Co atoms. There are a spread of Co–Co bond distances ranging from 2.39–2.77 Å.
Co7Hf2 is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 6-coordinate geometry to fourteen Co atoms. There are a spread of Hf–Co bond distances ranging from 2.72–2.87 Å. In the second Hf site, Hf is bonded in a 6-coordinate geometry to fourteen Co atoms. There are a spread of Hf–Co bond distances ranging from 2.73–2.87 Å. There are four inequivalent Co sites. In the first Co site, Co is bonded to four Hf and eight Co atoms to form a mixture of corner, edge, and face-sharing CoHf4Co8 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.32–2.49 Å. In the second Co site, Co is bonded in a 12-coordinate geometry to four equivalent Hf and eight Co atoms. There are a spread of Co–Co bond distances ranging from 2.35–2.76 Å. In the third Co site, Co is bonded in a 12-coordinate geometry to four equivalent Hf and eight Co atoms. There are a spread of Co–Co bond distances ranging from 2.38–2.78 Å. In the fourth Co site, Co is bonded to four Hf and eight Co atoms to form a mixture of corner, edge, and face-sharing CoHf4Co8 cuboctahedra.