DOE OSTI2020
K3B12H4Br(H2)4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional and consists of eight hydrogen molecules and one K3B12H4Br framework. In the K3B12H4Br framework, there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a square co-planar geometry to four B1- atoms. There are two shorter (3.06 Å) and two longer (3.07 Å) K–B bond lengths. In the second K1+ site, K1+ is bonded in a 2-coordinate geometry to six B1- and two H+0.83+ atoms. There are two shorter (2.95 Å) and four longer (3.22 Å) K–B bond lengths. Both K–H bond lengths are 3.03 Å. In the third K1+ site, K1+ is bonded in a rectangular see-saw-like geometry to four B1- atoms. There are two shorter (3.06 Å) and two longer (3.07 Å) K–B bond lengths. There are four inequivalent B1- sites. In the first B1- site, B1- is bonded in a distorted single-bond geometry to one K1+, one B1-, and one H+0.83+ atom. The B–B bond length is 1.59 Å. The B–H bond length is 1.47 Å. In the second B1- site, B1- is bonded in a distorted single-bond geometry to two K1+ and one H+0.83+ atom. The B–H bond length is 1.38 Å. In the third B1- site, B1- is bonded in a distorted single-bond geometry to one K1+ and one H+0.83+ atom. The B–H bond length is 1.61 Å. In the fourth B1- site, B1- is bonded in a distorted L-shaped geometry to one B1-, one H+0.83+, and one Br1- atom. The B–H bond length is 1.60 Å. The B–Br bond length is 2.27 Å. There are four inequivalent H+0.83+ sites. In the first H+0.83+ site, H+0.83+ is bonded in a 4-coordinate geometry to four B1- atoms. The H–B bond length is 1.60 Å. In the second H+0.83+ site, H+0.83+ is bonded in an L-shaped geometry to one K1+ and two equivalent B1- atoms. In the third H+0.83+ site, H+0.83+ is bonded in a 4-coordinate geometry to four B1- atoms. There is one shorter (1.47 Å) and two longer (1.61 Å) H–B bond length. In the fourth H+0.83+ site, H+0.83+ is bonded in an L-shaped geometry to one K1+ and two equivalent B1- atoms. Both H–B bond lengths are 1.38 Å. Br1- is bonded in a linear geometry to two equivalent B1- atoms.