Materials Data on FeH8N2F5 by Materials Project
(NH4)2FeF5 crystallizes in the orthorhombic Pnma space group. The structure is one-dimensional and consists of four ammonia molecules; four hydrogen molecules; and two FeNH7F5 ribbons oriented in the (0, 1, 0) direction. In each FeNH7F5 ribbon, Fe3+ is bonded to six F1- atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are a spread of Fe–F bond distances ranging from 1.87–2.07 Å. N3- is bonded in a distorted trigonal bipyramidal geometry to five H1+ atoms. There are a spread of N–H bond distances ranging from 1.02–1.48 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one H1+ and one F1- atom. The H–H bond length is 1.04 Å. The H–F bond length is 1.13 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a bent 120 degrees geometry to one N3- and one H1+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a bent 150 degrees geometry to two equivalent Fe3+ atoms. In the second F1- site, F1- is bonded in a distorted single-bond geometry to one Fe3+ and one H1+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Fe3+ atom.