Materials Data on MgAlH4O2F5 by Materials Project
MgAlH4O2F5 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Mg2+ is bonded to two equivalent O2- and four equivalent F1- atoms to form MgO2F4 octahedra that share corners with four equivalent AlF6 octahedra. The corner-sharing octahedral tilt angles are 43°. Both Mg–O bond lengths are 2.09 Å. All Mg–F bond lengths are 2.02 Å. Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with two equivalent AlF6 octahedra and corners with four equivalent MgO2F4 octahedra. The corner-sharing octahedra tilt angles range from 29–43°. There is four shorter (1.82 Å) and two longer (1.86 Å) Al–F bond length. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a distorted water-like geometry to one Mg2+ and two equivalent H1+ atoms. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one Al3+ atom. In the second F1- site, F1- is bonded in a bent 150 degrees geometry to two equivalent Al3+ atoms.