Rb2Fe4O7 crystallizes in the trigonal P-31m space group. Rb(1) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form FeO4 tetrahedra that share corners with six equivalent Fe(2)O6 octahedra and  a cornercorner with one Fe(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. In the second Fe site, Fe(2) is bonded to six equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Fe(1)O4 tetrahedra and edges with three equivalent Fe(2)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Rb(1), one Fe(1), and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a linear geometry to six equivalent Rb(1) and two equivalent Fe(1) atoms.
Rb2Fe4O7 crystallizes in the trigonal P-31m space group. Rb(1) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. All Rb(1)-O(2) bond lengths are 3.10 Å. All Rb(1)-O(1) bond lengths are 2.96 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form FeO4 tetrahedra that share corners with six equivalent Fe(2)O6 octahedra and  a cornercorner with one Fe(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. The Fe(1)-O(2) bond length is 1.93 Å. All Fe(1)-O(1) bond lengths are 1.93 Å. In the second Fe site, Fe(2) is bonded to six equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Fe(1)O4 tetrahedra and edges with three equivalent Fe(2)O6 octahedra. All Fe(2)-O(1) bond lengths are 2.08 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Rb(1), one Fe(1), and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a linear geometry to six equivalent Rb(1) and two equivalent Fe(1) atoms.