DOE OSTI2020
CsRb2Au7 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs1+ is bonded in a 8-coordinate geometry to two equivalent Rb1+ and twelve Au+0.43- atoms. Both Cs–Rb bond lengths are 3.77 Å. There are a spread of Cs–Au bond distances ranging from 3.63–4.16 Å. There are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded to twelve Au+0.43- atoms to form RbAu12 cuboctahedra that share corners with four equivalent RbAu12 cuboctahedra, faces with two equivalent RbAu12 cuboctahedra, and faces with eight equivalent AuCs2Rb4Au6 cuboctahedra. There are a spread of Rb–Au bond distances ranging from 3.53–3.75 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to two equivalent Cs1+ and twelve Au+0.43- atoms. There are a spread of Rb–Au bond distances ranging from 3.61–4.15 Å. There are four inequivalent Au+0.43- sites. In the first Au+0.43- site, Au+0.43- is bonded in a 10-coordinate geometry to two equivalent Cs1+, three Rb1+, and five Au+0.43- atoms. There are a spread of Au–Au bond distances ranging from 2.71–2.95 Å. In the second Au+0.43- site, Au+0.43- is bonded in a 10-coordinate geometry to one Cs1+, four Rb1+, and five Au+0.43- atoms. There are a spread of Au–Au bond distances ranging from 2.69–2.88 Å. In the third Au+0.43- site, Au+0.43- is bonded to two equivalent Cs1+, four Rb1+, and six Au+0.43- atoms to form AuCs2Rb4Au6 cuboctahedra that share corners with ten equivalent AuCs2Rb4Au6 cuboctahedra, edges with two equivalent AuCs2Rb4Au6 cuboctahedra, faces with two equivalent AuCs2Rb4Au6 cuboctahedra, and faces with four equivalent RbAu12 cuboctahedra. There are one shorter (2.85 Å) and one longer (2.87 Å) Au–Au bond lengths. In the fourth Au+0.43- site, Au+0.43- is bonded in a body-centered cubic geometry to two equivalent Cs1+, two equivalent Rb1+, and four Au+0.43- atoms.