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SmB2 is hexagonal omega structure structured and crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Sm is bonded to twelve equivalent B atoms to form a mixture of edge and face-sharing SmB12 cuboctahedra. All Sm–B bond lengths are 2.79 Å. B is bonded in a 9-coordinate geometry to six equivalent Sm and three equivalent B atoms. All B–B bond lengths are 1.92 Å.
Sm2B5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 12-coordinate geometry to twelve B atoms. There are a spread of Sm–B bond distances ranging from 2.65–2.92 Å. In the second Sm site, Sm is bonded in a 12-coordinate geometry to twelve B atoms. There are a spread of Sm–B bond distances ranging from 2.66–3.09 Å. There are five inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to four Sm and five B atoms. There are a spread of B–B bond distances ranging from 1.75–1.82 Å. In the second B site, B is bonded in a 9-coordinate geometry to four Sm and five B atoms. There are a spread of B–B bond distances ranging from 1.76–1.84 Å. In the third B site, B is bonded in a 3-coordinate geometry to six Sm and three B atoms. The B–B bond length is 1.84 Å. In the fourth B site, B is bonded in a 9-coordinate geometry to four Sm and five B atoms. The B–B bond length is 1.68 Å. In the fifth B site, B is bonded in a 8-coordinate geometry to six Sm and two B atoms. The B–B bond length is 1.66 Å.
SmB6 is Calcium hexaboride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Sm is bonded in a 1-coordinate geometry to twenty-four equivalent B atoms. All Sm–B bond lengths are 3.03 Å. B is bonded in a 1-coordinate geometry to four equivalent Sm and five equivalent B atoms. There is one shorter (1.64 Å) and four longer (1.75 Å) B–B bond length.
SmB12 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sm is bonded in a 1-coordinate geometry to twenty-four equivalent B atoms. All Sm–B bond lengths are 2.81 Å. B is bonded in a 7-coordinate geometry to two equivalent Sm and five equivalent B atoms. There is one shorter (1.74 Å) and four longer (1.80 Å) B–B bond length.
SmB4 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Sm is bonded in a 4-coordinate geometry to eighteen B atoms. There are a spread of Sm–B bond distances ranging from 2.76–3.10 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 1-coordinate geometry to four equivalent Sm and five B atoms. There is one shorter (1.67 Å) and four longer (1.77 Å) B–B bond length. In the second B site, B is bonded in a 9-coordinate geometry to four equivalent Sm and five B atoms. There is one shorter (1.74 Å) and two longer (1.82 Å) B–B bond length. In the third B site, B is bonded in a distorted trigonal planar geometry to six equivalent Sm and three B atoms. The B–B bond length is 1.78 Å.