Materials Data on FeHgO2F5 by Materials Project
FeHgO2F5 crystallizes in the orthorhombic Pbam space group. The structure is two-dimensional and consists of two FeHgO2F5 sheets oriented in the (0, 0, 1) direction. Fe is bonded to six F atoms to form FeF6 octahedra that share corners with two equivalent FeF6 octahedra and corners with four equivalent HgO2F4 octahedra. The corner-sharing octahedra tilt angles range from 0–50°. There is four shorter (1.94 Å) and two longer (1.96 Å) Fe–F bond length. Hg is bonded to two equivalent O and four equivalent F atoms to form distorted HgO2F4 octahedra that share corners with four equivalent FeF6 octahedra and edges with two equivalent HgO2F4 octahedra. The corner-sharing octahedral tilt angles are 50°. Both Hg–O bond lengths are 2.12 Å. All Hg–F bond lengths are 2.57 Å. O is bonded in a single-bond geometry to one Hg atom. There are three inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Fe atom. In the second F site, F is bonded in a distorted single-bond geometry to one Fe and two equivalent Hg atoms. In the third F site, F is bonded in a linear geometry to two equivalent Fe atoms.