Materials Data on Mn9(Si2O9)2 by Materials Project

Mn9(Si2O9)2 is Ilmenite-like structured and crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are nine inequivalent Mn+2.22+ sites. In the first Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four MnO6 octahedra, corners with two SiO4 tetrahedra, edges with four MnO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–69°. There are a spread of Mn–O bond distances ranging from 2.19–2.27 Å. In the second Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four MnO6 octahedra, corners with two SiO4 tetrahedra, edges with four MnO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–71°. There are a spread of Mn–O bond distances ranging from 2.20–2.24 Å. In the third Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four MnO6 octahedra, corners with two SiO4 tetrahedra, edges with four MnO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–72°. There are a spread of Mn–O bond distances ranging from 2.20–2.30 Å. In the fourth Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with eight MnO6 octahedra, corners with three SiO4 tetrahedra, edges with two MnO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–71°. There are a spread of Mn–O bond distances ranging from 2.08–2.45 Å. In the fifth Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with six MnO6 octahedra, corners with three SiO4 tetrahedra, edges with three MnO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–72°. There are a spread of Mn–O bond distances ranging from 2.08–2.33 Å. In the sixth Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with eight MnO6 octahedra, corners with four SiO4 tetrahedra, edges with two MnO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–67°. There are a spread of Mn–O bond distances ranging from 2.14–2.36 Å. In the seventh Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with eight MnO6 octahedra, corners with four SiO4 tetrahedra, edges with two MnO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–69°. There are a spread of Mn–O bond distances ranging from 2.14–2.42 Å. In the eighth Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four MnO6 octahedra, corners with two SiO4 tetrahedra, edges with four MnO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–56°. There are a spread of Mn–O bond distances ranging from 1.95–2.28 Å. In the ninth Mn+2.22+ site, Mn+2.22+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six MnO6 octahedra, corners with two SiO4 tetrahedra, edges with three MnO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–59°. There are a spread of Mn–O bond distances ranging from 1.94–2.34 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MnO6 octahedra and edges with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MnO6 octahedra and edges with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 51–63°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MnO6 octahedra and edges with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 7–63°. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MnO6 octahedra and edges with three MnO6 octahedra. The corner-sharing octahedra tilt angles range from 52–65°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+2.22+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+2.22+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+2.22+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+2.22+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+2.22+ and one Si4+ atom. In the sixteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to three Mn+2.22+ and one Si4+ atom. In the seventeenth O2- site, O2- is bonded in a trigonal planar geometry to three Mn+2.22+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mn+2.22+ atoms.