Materials Data on K2RbCO3F by Materials Project
RbK2CO3F crystallizes in the monoclinic C2 space group. The structure is three-dimensional. Rb1+ is bonded to five O2- and two equivalent F1- atoms to form distorted RbO5F2 pentagonal bipyramids that share corners with two equivalent RbO5F2 pentagonal bipyramids, corners with four KO5F2 pentagonal bipyramids, edges with two equivalent RbO5F2 pentagonal bipyramids, edges with four KO5F2 pentagonal bipyramids, and faces with four KO5F2 pentagonal bipyramids. There are a spread of Rb–O bond distances ranging from 2.92–3.04 Å. There are one shorter (2.72 Å) and one longer (2.73 Å) Rb–F bond lengths. There are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to five O2- and two equivalent F1- atoms to form distorted KO5F2 pentagonal bipyramids that share corners with two equivalent KO5F2 pentagonal bipyramids, corners with four equivalent RbO5F2 pentagonal bipyramids, edges with two equivalent KO5F2 pentagonal bipyramids, edges with four equivalent RbO5F2 pentagonal bipyramids, and faces with four equivalent KO5F2 pentagonal bipyramids. There are a spread of K–O bond distances ranging from 2.88–3.03 Å. Both K–F bond lengths are 2.66 Å. In the second K1+ site, K1+ is bonded to five O2- and two equivalent F1- atoms to form distorted KO5F2 pentagonal bipyramids that share corners with two equivalent RbO5F2 pentagonal bipyramids, corners with four KO5F2 pentagonal bipyramids, edges with two equivalent RbO5F2 pentagonal bipyramids, edges with four KO5F2 pentagonal bipyramids, faces with two equivalent RbO5F2 pentagonal bipyramids, and faces with two equivalent KO5F2 pentagonal bipyramids. There are a spread of K–O bond distances ranging from 2.90–3.03 Å. There are one shorter (2.62 Å) and one longer (2.63 Å) K–F bond lengths. In the third K1+ site, K1+ is bonded to five O2- and two equivalent F1- atoms to form distorted KO5F2 pentagonal bipyramids that share corners with six KO5F2 pentagonal bipyramids, edges with six KO5F2 pentagonal bipyramids, and faces with four equivalent RbO5F2 pentagonal bipyramids. There are a spread of K–O bond distances ranging from 2.89–3.03 Å. Both K–F bond lengths are 2.67 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.31 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.31 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Rb1+, three K1+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Rb1+, three K1+, and one C4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Rb1+, four K1+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Rb1+, three K1+, and one C4+ atom. F1- is bonded to two equivalent Rb1+ and four K1+ atoms to form corner-sharing FK4Rb2 octahedra. The corner-sharing octahedra tilt angles range from 21–22°.