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UB2 is hexagonal omega structure structured and crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. U6+ is bonded to twelve equivalent B3- atoms to form a mixture of edge and face-sharing UB12 cuboctahedra. All U–B bond lengths are 2.68 Å. B3- is bonded in a 3-coordinate geometry to six equivalent U6+ and three equivalent B3- atoms. All B–B bond lengths are 1.78 Å.
UB12 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. U6+ is bonded in a 1-coordinate geometry to twenty-four equivalent B+0.50- atoms. All U–B bond lengths are 2.77 Å. B+0.50- is bonded in a 7-coordinate geometry to two equivalent U6+ and five equivalent B+0.50- atoms. There is one shorter (1.69 Å) and four longer (1.79 Å) B–B bond length.
UB4 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. U6+ is bonded in a 12-coordinate geometry to eighteen B+1.50- atoms. There are a spread of U–B bond distances ranging from 2.67–2.97 Å. There are three inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a distorted trigonal planar geometry to six equivalent U6+ and three B+1.50- atoms. There is two shorter (1.68 Å) and one longer (1.73 Å) B–B bond length. In the second B+1.50- site, B+1.50- is bonded in a 1-coordinate geometry to four equivalent U6+ and five B+1.50- atoms. There is one shorter (1.58 Å) and four longer (1.75 Å) B–B bond length. In the third B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent U6+ and five B+1.50- atoms. Both B–B bond lengths are 1.82 Å.