Materials Data on KRb2SiF7 by Materials Project
Rb2KSiF7 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded to six F1- atoms to form distorted RbF6 octahedra that share corners with four SiF6 octahedra and corners with six equivalent RbF6 octahedra. The corner-sharing octahedra tilt angles range from 0–69°. There are a spread of Rb–F bond distances ranging from 2.91–3.04 Å. In the second Rb1+ site, Rb1+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of Rb–F bond distances ranging from 2.82–3.02 Å. K1+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of K–F bond distances ranging from 2.78–3.01 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to six F1- atoms to form SiF6 octahedra that share corners with four equivalent RbF6 octahedra. The corner-sharing octahedral tilt angles are 69°. All Si–F bond lengths are 1.72 Å. In the second Si4+ site, Si4+ is bonded to six F1- atoms to form SiF6 octahedra that share corners with four equivalent RbF6 octahedra. The corner-sharing octahedral tilt angles are 68°. There is two shorter (1.72 Å) and four longer (1.73 Å) Si–F bond length. There are seven inequivalent F1- sites. In the first F1- site, F1- is bonded to four Rb1+ and two equivalent K1+ atoms to form corner-sharing FK2Rb4 octahedra. The corner-sharing octahedra tilt angles range from 0–26°. There are two shorter (2.88 Å) and two longer (2.91 Å) F–Rb bond lengths. Both F–K bond lengths are 2.90 Å. In the second F1- site, F1- is bonded in a distorted single-bond geometry to one Rb1+, two equivalent K1+, and one Si4+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to two equivalent Rb1+, one K1+, and one Si4+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to four Rb1+ and one Si4+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to two equivalent Rb1+, two equivalent K1+, and one Si4+ atom. In the sixth F1- site, F1- is bonded to four Rb1+ and two equivalent K1+ atoms to form corner-sharing FK2Rb4 octahedra. The corner-sharing octahedra tilt angles range from 0–26°. In the seventh F1- site, F1- is bonded to four Rb1+ and two equivalent K1+ atoms to form corner-sharing FK2Rb4 octahedra. The corner-sharing octahedra tilt angles range from 0–26°. Both F–Rb bond lengths are 2.91 Å.