Materials Data on K4I2O9 by Materials Project

Abstract

K4O9I2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent K sites. In the first K site, K is bonded to six equivalent O atoms to form KO6 octahedra that share corners with six equivalent IO6 octahedra and faces with two equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 10°. All K–O bond lengths are 2.58 Å. In the second K site, K is bonded to twelve O atoms to form distorted KO12 cuboctahedra that share corners with six equivalent KO12 cuboctahedra, faces with two equivalent KO6 octahedra, and faces with six equivalent IO6 octahedra. There are six shorter (3.09 Å) and six longer (3.17 Å) K–O bond lengths. In the third K site, K is bonded in a 12-coordinate geometry to twelve O atoms. There are a spread of K–O bond distances ranging from 3.16–3.43 Å. There are two inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to five K and one I atom. The O–I bond length is 1.83 Å. In the second O site, O is bonded in a distorted L-shaped geometry to four K and two equivalent I atoms. Both O–I bond lengths are 2.05 Å. I is bonded to six O atoms to form distorted IO6 octahedra that share corners with three equivalent KO6 octahedra, faces with three equivalent KO12 cuboctahedra, and a faceface with one IO6 octahedra. The corner-sharing octahedral tilt angles are 10°.