Materials Data on K2Fe2P2O7F2 by Materials Project

Abstract

K2Fe2P2O7F2 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. K1+ is bonded in a 5-coordinate geometry to three O2- and two equivalent F1- atoms. There are a spread of K–O bond distances ranging from 2.77–3.01 Å. There are one shorter (2.61 Å) and one longer (2.68 Å) K–F bond lengths. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to four O2- and two equivalent F1- atoms to form distorted FeO4F2 octahedra that share edges with two equivalent PO4 tetrahedra. There are two shorter (2.28 Å) and two longer (2.39 Å) Fe–O bond lengths. Both Fe–F bond lengths are 1.97 Å. In the second Fe2+ site, Fe2+ is bonded in a distorted square co-planar geometry to six O2- atoms. There are four shorter (2.09 Å) and two longer (2.62 Å) Fe–O bond lengths. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one PO4 tetrahedra and an edgeedge with one FeO4F2 octahedra. There are a spread of P–O bond distances ranging from 1.53–1.61 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Fe2+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one K1+, two Fe2+, and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Fe2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. F1- is bonded in a distorted trigonal non-coplanar geometry to two equivalent K1+ and one Fe2+ atom.