Materials Data on Na6Fe2As(CO4)4 by Materials Project
Na6Fe2As(CO4)4 crystallizes in the cubic Fd-3 space group. The structure is three-dimensional. Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with eight equivalent NaO6 octahedra, edges with two equivalent FeO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–88°. There are a spread of Na–O bond distances ranging from 2.46–2.56 Å. Fe+2.50+ is bonded to six equivalent O2- atoms to form FeO6 octahedra that share edges with six equivalent NaO6 octahedra. All Fe–O bond lengths are 2.14 Å. C4+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All C–O bond lengths are 1.30 Å. As5+ is bonded to four equivalent O2- atoms to form AsO4 tetrahedra that share edges with six equivalent NaO6 octahedra. All As–O bond lengths are 1.73 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na1+, one Fe+2.50+, and one C4+ atom. In the second O2- site, O2- is bonded to three equivalent Na1+ and one As5+ atom to form distorted edge-sharing ONa3As trigonal pyramids.