DOE OSTI2020
KMn4O8 crystallizes in the triclinic P1 space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.64–3.08 Å. There are four inequivalent Mn+3.75+ sites. In the first Mn+3.75+ site, Mn+3.75+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent MnO6 octahedra, a cornercorner with one MnO5 trigonal bipyramid, edges with three MnO5 trigonal bipyramids, and a faceface with one MnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Mn–O bond distances ranging from 1.87–2.04 Å. In the second Mn+3.75+ site, Mn+3.75+ is bonded to five O2- atoms to form MnO5 trigonal bipyramids that share corners with three equivalent MnO6 octahedra, corners with two equivalent MnO5 trigonal bipyramids, and edges with two equivalent MnO6 octahedra. The corner-sharing octahedra tilt angles range from 37–54°. There are a spread of Mn–O bond distances ranging from 1.88–2.06 Å. In the third Mn+3.75+ site, Mn+3.75+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent MnO6 octahedra, corners with five MnO5 trigonal bipyramids, an edgeedge with one MnO5 trigonal bipyramid, and a faceface with one MnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of Mn–O bond distances ranging from 1.87–2.09 Å. In the fourth Mn+3.75+ site, Mn+3.75+ is bonded to five O2- atoms to form distorted MnO5 trigonal bipyramids that share corners with three MnO6 octahedra, corners with two equivalent MnO5 trigonal bipyramids, and edges with two MnO6 octahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Mn–O bond distances ranging from 1.83–2.29 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and three Mn+3.75+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two Mn+3.75+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Mn+3.75+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one K1+ and three Mn+3.75+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to one K1+ and two Mn+3.75+ atoms. In the sixth O2- site, O2- is bonded in a trigonal pyramidal geometry to four Mn+3.75+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and three Mn+3.75+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and three Mn+3.75+ atoms.