Rb4Fe2O5 crystallizes in the monoclinic C2/c space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Fe(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing FeO4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), two equivalent Rb(3), and one Fe(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), two equivalent Rb(2), two equivalent Rb(3), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a distorted linear geometry to four equivalent Rb(3) and two equivalent Fe(1) atoms.
Rb4Fe2O5 crystallizes in the monoclinic C2/c space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Rb(1)-O(2) bond lengths are 3.21 Å. There are two shorter (2.75 Å) and two longer (2.99 Å) Rb(1)-O(1) bond lengths. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. There are two shorter (2.96 Å) and two longer (3.08 Å) Rb(2)-O(1) bond lengths. There are two shorter (3.24 Å) and two longer (3.50 Å) Rb(2)-O(2) bond lengths. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There is one shorter (3.02 Å) and one longer (3.10 Å) Rb(3)-O(1) bond length. There is one shorter (2.74 Å) and one longer (3.06 Å) Rb(3)-O(2) bond length. There is one shorter (2.99 Å) and one longer (3.01 Å) Rb(3)-O(3) bond length. Fe(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing FeO4 tetrahedra. The Fe(1)-O(1) bond length is 1.81 Å. The Fe(1)-O(3) bond length is 1.90 Å. Both Fe(1)-O(2) bond lengths are 1.94 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), two equivalent Rb(3), and one Fe(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), two equivalent Rb(2), two equivalent Rb(3), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a distorted linear geometry to four equivalent Rb(3) and two equivalent Fe(1) atoms.