Materials Data on KCr12Si8ClO28 by Materials Project
KCr12Si8O28Cl crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. K1+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are four shorter (2.63 Å) and four longer (2.98 Å) K–O bond lengths. There are three inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded in a distorted rectangular see-saw-like geometry to four O2- and one Cl1- atom. There are two shorter (2.06 Å) and two longer (2.07 Å) Cr–O bond lengths. The Cr–Cl bond length is 3.08 Å. In the second Cr2+ site, Cr2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.05 Å) and two longer (2.06 Å) Cr–O bond lengths. In the third Cr2+ site, Cr2+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.05 Å) and two longer (2.06 Å) Cr–O bond lengths. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one K1+, two equivalent Cr2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Cr2+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cr2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cr2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one K1+ and two Si4+ atoms. Cl1- is bonded in a 4-coordinate geometry to four equivalent Cr2+ atoms.