Rb2Ce2Fe4O11 crystallizes in the orthorhombic Cmmm space group. Rb(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(4) atoms to form distorted RbO12 cuboctahedra that share corners with four equivalent Rb(1)O12 cuboctahedra, faces with four equivalent Rb(1)O12 cuboctahedra, faces with four equivalent Fe(2)O6 octahedra, and faces with four equivalent Fe(1)O5 trigonal bipyramids. Ce(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted FeO5 trigonal bipyramids that share corners with three equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-30°. In the second Fe site, Fe(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form distorted FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-19°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Rb(1), two equivalent Ce(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Rb(1), two equivalent Ce(1), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Ce(1), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded to four equivalent Rb(1), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner and edge-sharing ORb4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent Ce(1) and two equivalent Fe(2) atoms.
Rb2Ce2Fe4O11 crystallizes in the orthorhombic Cmmm space group. Rb(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(4) atoms to form distorted RbO12 cuboctahedra that share corners with four equivalent Rb(1)O12 cuboctahedra, faces with four equivalent Rb(1)O12 cuboctahedra, faces with four equivalent Fe(2)O6 octahedra, and faces with four equivalent Fe(1)O5 trigonal bipyramids. Both Rb(1)-O(2) bond lengths are 3.26 Å. Both Rb(1)-O(3) bond lengths are 3.04 Å. All Rb(1)-O(1) bond lengths are 3.16 Å. All Rb(1)-O(4) bond lengths are 2.81 Å. Ce(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. Both Ce(1)-O(2) bond lengths are 2.53 Å. Both Ce(1)-O(3) bond lengths are 2.52 Å. Both Ce(1)-O(5) bond lengths are 2.73 Å. All Ce(1)-O(1) bond lengths are 2.46 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted FeO5 trigonal bipyramids that share corners with three equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-30°. The Fe(1)-O(4) bond length is 1.90 Å. Both Fe(1)-O(1) bond lengths are 1.99 Å. Both Fe(1)-O(2) bond lengths are 2.08 Å. In the second Fe site, Fe(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form distorted FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O5 trigonal bipyramids, and faces with four equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-19°. The Fe(2)-O(4) bond length is 1.96 Å. The Fe(2)-O(5) bond length is 1.98 Å. Both Fe(2)-O(1) bond lengths are 2.17 Å. Both Fe(2)-O(3) bond lengths are 1.99 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Rb(1), two equivalent Ce(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Rb(1), two equivalent Ce(1), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Ce(1), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded to four equivalent Rb(1), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner and edge-sharing ORb4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent Ce(1) and two equivalent Fe(2) atoms.