Ca(FeO2)4 is beta indium sulfide-derived structured and crystallizes in the trigonal R-3m space group. Ca(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form edge-sharing FeO6 octahedra. In the second Fe site, Fe(2) is bonded to six equivalent O(1) atoms to form edge-sharing FeO6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to three equivalent Fe(1) atoms.
Ca(FeO2)4 is beta indium sulfide-derived structured and crystallizes in the trigonal R-3m space group. Ca(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. All Ca(1)-O(1) bond lengths are 2.42 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form edge-sharing FeO6 octahedra. Both Fe(1)-O(2) bond lengths are 1.96 Å. All Fe(1)-O(1) bond lengths are 1.95 Å. In the second Fe site, Fe(2) is bonded to six equivalent O(1) atoms to form edge-sharing FeO6 octahedra. All Fe(2)-O(1) bond lengths are 1.98 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to three equivalent Fe(1) atoms.