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HfB2 is hexagonal omega structure structured and crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Hf is bonded to twelve equivalent B atoms to form a mixture of edge and face-sharing HfB12 cuboctahedra. All Hf–B bond lengths are 2.52 Å. B is bonded in a 9-coordinate geometry to six equivalent Hf and three equivalent B atoms. All B–B bond lengths are 1.82 Å.
HfB is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded to six equivalent B atoms to form a mixture of edge and corner-sharing HfB6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Hf–B bond lengths are 2.42 Å. B is bonded to six equivalent Hf atoms to form a mixture of edge and corner-sharing BHf6 octahedra. The corner-sharing octahedral tilt angles are 0°.
HfB6 is Calcium hexaboride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hf is bonded in a 1-coordinate geometry to twenty-four equivalent B atoms. All Hf–B bond lengths are 2.96 Å. B is bonded in a 1-coordinate geometry to four equivalent Hf and five equivalent B atoms. There is one shorter (1.59 Å) and four longer (1.73 Å) B–B bond length.