Materials Data on KCa4Si8H16O28F by Materials Project

(KCa4Si8(H4O7)4)2F2 crystallizes in the tetragonal P4/mnc space group. The structure is three-dimensional and consists of two hydrofluoric acid molecules and one KCa4Si8(H4O7)4 framework. In the KCa4Si8(H4O7)4 framework, K1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 2.71 Å. Ca2+ is bonded in a 2-coordinate geometry to two equivalent H1+ and four O2- atoms. Both Ca–H bond lengths are 2.42 Å. There are two shorter (2.19 Å) and two longer (2.60 Å) Ca–O bond lengths. Si4+ is bonded to five O2- atoms to form distorted corner-sharing SiO5 trigonal bipyramids. There are a spread of Si–O bond distances ranging from 1.62–1.92 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one Ca2+ and one H1+ atom. The H–H bond length is 0.76 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Ca2+, one Si4+, and one H1+ atom.