Rb5FeO4 crystallizes in the orthorhombic Pmn2_1 space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second Rb site, Rb(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(3) atoms. In the third Rb site, Rb(3) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(3) atoms. Fe(1) is bonded in a tetrahedral geometry to one O(1), one O(2), and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a 8-coordinate geometry to one Rb(3), two equivalent Rb(2), four equivalent Rb(1), and one Fe(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Rb(3), two equivalent Rb(1), two equivalent Rb(2), and one Fe(1) atom.
Rb5FeO4 crystallizes in the orthorhombic Pmn2_1 space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. The Rb(1)-O(1) bond length is 3.00 Å. There is one shorter (2.94 Å) and one longer (3.18 Å) Rb(1)-O(2) bond length. There is one shorter (2.83 Å) and one longer (3.00 Å) Rb(1)-O(3) bond length. In the second Rb site, Rb(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(3) atoms. The Rb(2)-O(1) bond length is 2.87 Å. The Rb(2)-O(2) bond length is 3.07 Å. There is one shorter (2.76 Å) and one longer (2.77 Å) Rb(2)-O(3) bond length. In the third Rb site, Rb(3) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(3) atoms. The Rb(3)-O(2) bond length is 2.86 Å. Both Rb(3)-O(3) bond lengths are 2.93 Å. Fe(1) is bonded in a tetrahedral geometry to one O(1), one O(2), and two equivalent O(3) atoms. The Fe(1)-O(1) bond length is 1.94 Å. The Fe(1)-O(2) bond length is 1.98 Å. Both Fe(1)-O(3) bond lengths are 1.96 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a 8-coordinate geometry to one Rb(3), two equivalent Rb(2), four equivalent Rb(1), and one Fe(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Rb(3), two equivalent Rb(1), two equivalent Rb(2), and one Fe(1) atom.