DOI: 10.17188/1707432
title: Materials Data on KRb2CO3F by Materials Project

description: Rb2KCO3F crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, 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 equivalent KO5F2 pentagonal bipyramids, edges with two equivalent RbO5F2 pentagonal bipyramids, edges with four equivalent KO5F2 pentagonal bipyramids, and faces with four equivalent RbO5F2 pentagonal bipyramids. There are a spread of Rb–O bond distances ranging from 2.95–3.10 Å. Both Rb–F bond lengths are 2.74 Å. In the second Rb1+ site, Rb1+ is bonded to five O2- and two equivalent F1- atoms to form distorted RbO5F2 pentagonal bipyramids that share corners with two equivalent KO5F2 pentagonal bipyramids, corners with four RbO5F2 pentagonal bipyramids, edges with two equivalent KO5F2 pentagonal bipyramids, edges with four RbO5F2 pentagonal bipyramids, faces with two equivalent RbO5F2 pentagonal bipyramids, and faces with two equivalent KO5F2 pentagonal bipyramids. There are a spread of Rb–O bond distances ranging from 2.94–3.10 Å. There are one shorter (2.76 Å) and one longer (2.77 Å) Rb–F bond lengths. In the third Rb1+ site, Rb1+ is bonded to five O2- and two equivalent F1- atoms to form distorted RbO5F2 pentagonal bipyramids that share corners with six RbO5F2 pentagonal bipyramids, edges with six RbO5F2 pentagonal bipyramids, and faces with four equivalent KO5F2 pentagonal bipyramids. There are a spread of Rb–O bond distances ranging from 2.94–3.10 Å. Both Rb–F bond lengths are 2.73 Å. 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 RbO5F2 pentagonal bipyramids, edges with two equivalent KO5F2 pentagonal bipyramids, edges with four RbO5F2 pentagonal bipyramids, and faces with four RbO5F2 pentagonal bipyramids. There are a spread of K–O bond distances ranging from 2.90–3.13 Å. There are one shorter (2.65 Å) and one longer (2.66 Å) K–F bond lengths. 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 three Rb1+, two equivalent K1+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+, two equivalent K1+, and one C4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four Rb1+, one K1+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+, two equivalent K1+, and one C4+ atom. 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 22–24°.