Rb5FeO4 crystallizes in the monoclinic P2_1/c space group. There are five inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted RbO4 trigonal pyramids that share corners with two equivalent Fe(1)O4 tetrahedra and  an edgeedge with one Fe(1)O4 tetrahedra. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), and two equivalent O(4) atoms. In the third Rb site, Rb(3) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. In the fourth Rb site, Rb(4) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. In the fifth Rb site, Rb(5) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with two equivalent Rb(1)O4 trigonal pyramids and  an edgeedge with one Rb(1)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(4), one Rb(5), and one Fe(1) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), one Rb(5), two equivalent Rb(3), and one Fe(1) atom. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(5), two equivalent Rb(4), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Rb(1), one Rb(4), one Rb(5), two equivalent Rb(2), and one Fe(1) atom.
Rb5FeO4 crystallizes in the monoclinic P2_1/c space group. There are five inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted RbO4 trigonal pyramids that share corners with two equivalent Fe(1)O4 tetrahedra and  an edgeedge with one Fe(1)O4 tetrahedra. The Rb(1)-O(1) bond length is 2.83 Å. The Rb(1)-O(2) bond length is 2.95 Å. The Rb(1)-O(3) bond length is 2.82 Å. The Rb(1)-O(4) bond length is 2.72 Å. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), and two equivalent O(4) atoms. The Rb(2)-O(1) bond length is 2.81 Å. The Rb(2)-O(2) bond length is 3.04 Å. The Rb(2)-O(3) bond length is 2.98 Å. There is one shorter (3.03 Å) and one longer (3.39 Å) Rb(2)-O(4) bond length. In the third Rb site, Rb(3) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. The Rb(3)-O(1) bond length is 2.64 Å. The Rb(3)-O(3) bond length is 3.14 Å. There is one shorter (2.95 Å) and one longer (3.06 Å) Rb(3)-O(2) bond length. In the fourth Rb site, Rb(4) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. The Rb(4)-O(1) bond length is 2.71 Å. The Rb(4)-O(2) bond length is 3.32 Å. The Rb(4)-O(4) bond length is 3.11 Å. There is one shorter (2.89 Å) and one longer (3.01 Å) Rb(4)-O(3) bond length. In the fifth Rb site, Rb(5) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Rb(5)-O(1) bond length is 2.88 Å. The Rb(5)-O(2) bond length is 2.89 Å. The Rb(5)-O(3) bond length is 3.30 Å. The Rb(5)-O(4) bond length is 2.77 Å. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with two equivalent Rb(1)O4 trigonal pyramids and  an edgeedge with one Rb(1)O4 trigonal pyramid. The Fe(1)-O(1) bond length is 1.94 Å. The Fe(1)-O(2) bond length is 1.97 Å. The Fe(1)-O(3) bond length is 1.99 Å. The Fe(1)-O(4) bond length is 1.90 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(4), one Rb(5), and one Fe(1) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), one Rb(5), two equivalent Rb(3), and one Fe(1) atom. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(5), two equivalent Rb(4), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Rb(1), one Rb(4), one Rb(5), two equivalent Rb(2), and one Fe(1) atom.