Materials Data on KFe3H6(SO7)2 by Materials Project
KFe3H6(SO7)2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share corners with six equivalent SO4 tetrahedra and faces with six equivalent FeO6 octahedra. There are six shorter (2.91 Å) and six longer (3.03 Å) K–O bond lengths. Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent FeO6 octahedra, corners with two equivalent SO4 tetrahedra, and faces with two equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 46°. There are four shorter (2.02 Å) and two longer (2.08 Å) Fe–O bond lengths. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent KO12 cuboctahedra and corners with three equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There is one shorter (1.47 Å) and three longer (1.50 Å) S–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Fe3+, and one S6+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one K1+, two equivalent Fe3+, and one H1+ atom.