Rb3FeO3 crystallizes in the monoclinic P2_1/c 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(2), two equivalent O(1), and two equivalent O(3) atoms. In the second Rb site, Rb(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted RbO4 tetrahedra that share corners with four equivalent Fe(1)O4 tetrahedra and edges with two equivalent Rb(2)O4 tetrahedra. In the third Rb site, Rb(3) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(3) atoms. Fe(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with four equivalent Rb(2)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-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 6-coordinate geometry to one Rb(1), two equivalent Rb(2), two equivalent Rb(3), and one Fe(1) atom. In the third O site, O(3) is bonded to two equivalent Rb(1), two equivalent Rb(3), and two equivalent Fe(1) atoms to form a mixture of distorted edge and corner-sharing ORb4Fe2 octahedra. The corner-sharing octahedral tilt angles are 16°.
Rb3FeO3 crystallizes in the monoclinic P2_1/c 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(2), two equivalent O(1), and two equivalent O(3) atoms. The Rb(1)-O(2) bond length is 2.90 Å. There is one shorter (2.78 Å) and one longer (2.81 Å) Rb(1)-O(1) bond length. There is one shorter (3.00 Å) and one longer (3.07 Å) Rb(1)-O(3) bond length. In the second Rb site, Rb(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted RbO4 tetrahedra that share corners with four equivalent Fe(1)O4 tetrahedra and edges with two equivalent Rb(2)O4 tetrahedra. There is one shorter (2.68 Å) and one longer (2.71 Å) Rb(2)-O(1) bond length. There is one shorter (2.75 Å) and one longer (3.12 Å) Rb(2)-O(2) bond length. In the third Rb site, Rb(3) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(3) atoms. There is one shorter (2.93 Å) and one longer (3.05 Å) Rb(3)-O(2) bond length. There is one shorter (2.90 Å) and one longer (2.97 Å) Rb(3)-O(3) bond length. Fe(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with four equivalent Rb(2)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.89 Å. The Fe(1)-O(2) bond length is 1.90 Å. There is one shorter (2.00 Å) and one longer (2.02 Å) Fe(1)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-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 6-coordinate geometry to one Rb(1), two equivalent Rb(2), two equivalent Rb(3), and one Fe(1) atom. In the third O site, O(3) is bonded to two equivalent Rb(1), two equivalent Rb(3), and two equivalent Fe(1) atoms to form a mixture of distorted edge and corner-sharing ORb4Fe2 octahedra. The corner-sharing octahedral tilt angles are 16°.