Materials Data on Na4Fe2As(CO4)4 by Materials Project
Na4Fe2As(CO4)4 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to six O atoms to form distorted NaO6 octahedra that share corners with four equivalent NaO6 octahedra, edges with two equivalent FeO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–86°. There are a spread of Na–O bond distances ranging from 2.39–2.52 Å. In the second Na site, Na is bonded to six O atoms to form distorted NaO6 octahedra that share corners with four equivalent NaO6 octahedra, edges with two equivalent FeO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–86°. There are a spread of Na–O bond distances ranging from 2.39–2.59 Å. Fe is bonded to six O atoms to form FeO6 octahedra that share edges with four NaO6 octahedra. There are four shorter (2.04 Å) and two longer (2.06 Å) Fe–O bond lengths. C is bonded in a trigonal planar geometry to three O atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. As is bonded to four equivalent O atoms to form AsO4 tetrahedra that share edges with four NaO6 octahedra. All As–O bond lengths are 1.72 Å. There are four inequivalent O sites. In the first O site, O is bonded in a distorted T-shaped geometry to two Na and one As atom. In the second O site, O is bonded in a 3-coordinate geometry to one Na, one Fe, and one C atom. In the third O site, O is bonded in a 3-coordinate geometry to one Na, one Fe, and one C atom. In the fourth O site, O is bonded in a distorted rectangular see-saw-like geometry to two Na, one Fe, and one C atom.