DOE OSTI2020
Sc5Rh15B crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are three inequivalent Sc sites. In the first Sc site, Sc is bonded to twelve Rh atoms to form ScRh12 cuboctahedra that share corners with twelve ScRh12 cuboctahedra, edges with four equivalent RhSc4Rh8 cuboctahedra, faces with six ScRh12 cuboctahedra, and faces with four equivalent BRh6 octahedra. There are a spread of Sc–Rh bond distances ranging from 2.80–2.86 Å. In the second Sc site, Sc is bonded to twelve Rh atoms to form ScRh12 cuboctahedra that share corners with twelve ScRh12 cuboctahedra, edges with four equivalent RhSc4Rh8 cuboctahedra, faces with four equivalent RhSc4Rh8 cuboctahedra, and faces with six ScRh12 cuboctahedra. There are a spread of Sc–Rh bond distances ranging from 2.77–2.85 Å. In the third Sc site, Sc is bonded to twelve Rh atoms to form ScRh12 cuboctahedra that share corners with twelve ScRh12 cuboctahedra, edges with eight equivalent RhSc4Rh8 cuboctahedra, faces with four equivalent RhSc4Rh8 cuboctahedra, and faces with six ScRh12 cuboctahedra. There are eight shorter (2.79 Å) and four longer (2.85 Å) Sc–Rh bond lengths. There are six inequivalent Rh sites. In the first Rh site, Rh is bonded in a 1-coordinate geometry to four equivalent Sc and one B atom. The Rh–B bond length is 2.10 Å. In the second Rh site, Rh is bonded to four equivalent Sc and eight Rh atoms to form distorted RhSc4Rh8 cuboctahedra that share corners with eight RhSc4Rh8 cuboctahedra, edges with eight ScRh12 cuboctahedra, faces with four equivalent ScRh12 cuboctahedra, and faces with five RhSc4Rh8 cuboctahedra. There are four shorter (2.77 Å) and four longer (2.81 Å) Rh–Rh bond lengths. In the third Rh site, Rh is bonded to four equivalent Sc and eight equivalent Rh atoms to form distorted RhSc4Rh8 cuboctahedra that share corners with twelve RhSc4Rh8 cuboctahedra, edges with eight equivalent ScRh12 cuboctahedra, faces with four equivalent ScRh12 cuboctahedra, and faces with six RhSc4Rh8 cuboctahedra. All Rh–Rh bond lengths are 2.79 Å. In the fourth Rh site, Rh is bonded to four equivalent Sc and two equivalent B atoms to form a mixture of distorted edge, corner, and face-sharing RhSc4B2 octahedra. The corner-sharing octahedral tilt angles are 0°. Both Rh–B bond lengths are 2.01 Å. In the fifth Rh site, Rh is bonded in a distorted square co-planar geometry to four Sc and two equivalent Rh atoms. In the sixth Rh site, Rh is bonded in a distorted square co-planar geometry to four Sc and four Rh atoms. B is bonded to six Rh atoms to form BRh6 octahedra that share corners with four equivalent BRh6 octahedra and faces with eight equivalent ScRh12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°.