Rb8Mg(FeO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form distorted RbO4 tetrahedra that share corners with two equivalent Fe(2)O4 tetrahedra and edges with two equivalent Rb(8)O4 tetrahedra. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and one O(7) atom. In the third Rb site, Rb(3) is bonded in a distorted trigonal planar geometry to one O(1), one O(4), and one O(7) atom. In the fourth Rb site, Rb(4) is bonded in a 4-coordinate geometry to one O(2), one O(6), one O(7), and one O(8) atom. In the fifth Rb site, Rb(5) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. In the sixth Rb site, Rb(6) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(8) atom. In the seventh Rb site, Rb(7) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(5), one O(6), and one O(7) atom. In the eighth Rb site, Rb(8) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form RbO4 tetrahedra that share corners with two equivalent Fe(2)O4 tetrahedra and edges with two equivalent Rb(1)O4 tetrahedra. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), one O(4), and one O(5) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(5) atom. In the second Fe site, Fe(2) is bonded to one O(4), one O(6), one O(7), and one O(8) atom to form FeO4 tetrahedra that share corners with two equivalent Rb(1)O4 tetrahedra and corners with two equivalent Rb(8)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(3), one Rb(5), one Rb(6), one Rb(8), and one Fe(1) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Rb(2), one Rb(4), one Rb(5), one Rb(6), one Rb(7), one Mg(1), and one Fe(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(2), one Rb(5), one Rb(8), one Mg(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Rb(2), one Rb(3), one Rb(5), one Rb(7), one Mg(1), and one Fe(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Rb(2), one Rb(6), one Rb(7), one Mg(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(4), one Rb(7), one Rb(8), and one Fe(2) atom. In the seventh O site, O(7) is bonded in a distorted octahedral geometry to one Rb(2), one Rb(3), one Rb(4), one Rb(5), one Rb(7), and one Fe(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(4), one Rb(6), one Rb(8), and one Fe(2) atom.
Rb8Mg(FeO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form distorted RbO4 tetrahedra that share corners with two equivalent Fe(2)O4 tetrahedra and edges with two equivalent Rb(8)O4 tetrahedra. The Rb(1)-O(1) bond length is 2.88 Å. The Rb(1)-O(3) bond length is 2.95 Å. The Rb(1)-O(6) bond length is 2.77 Å. The Rb(1)-O(8) bond length is 3.11 Å. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and one O(7) atom. The Rb(2)-O(2) bond length is 3.02 Å. The Rb(2)-O(3) bond length is 2.91 Å. The Rb(2)-O(4) bond length is 2.97 Å. The Rb(2)-O(5) bond length is 2.88 Å. The Rb(2)-O(7) bond length is 2.77 Å. In the third Rb site, Rb(3) is bonded in a distorted trigonal planar geometry to one O(1), one O(4), and one O(7) atom. The Rb(3)-O(1) bond length is 2.79 Å. The Rb(3)-O(4) bond length is 2.99 Å. The Rb(3)-O(7) bond length is 2.85 Å. In the fourth Rb site, Rb(4) is bonded in a 4-coordinate geometry to one O(2), one O(6), one O(7), and one O(8) atom. The Rb(4)-O(2) bond length is 2.92 Å. The Rb(4)-O(6) bond length is 2.86 Å. The Rb(4)-O(7) bond length is 2.81 Å. The Rb(4)-O(8) bond length is 2.77 Å. In the fifth Rb site, Rb(5) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. The Rb(5)-O(1) bond length is 3.08 Å. The Rb(5)-O(2) bond length is 2.76 Å. The Rb(5)-O(3) bond length is 2.87 Å. The Rb(5)-O(4) bond length is 3.07 Å. The Rb(5)-O(7) bond length is 2.86 Å. In the sixth Rb site, Rb(6) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(8) atom. The Rb(6)-O(1) bond length is 3.22 Å. The Rb(6)-O(2) bond length is 3.44 Å. The Rb(6)-O(5) bond length is 3.08 Å. The Rb(6)-O(8) bond length is 2.70 Å. In the seventh Rb site, Rb(7) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(5), one O(6), and one O(7) atom. The Rb(7)-O(2) bond length is 3.01 Å. The Rb(7)-O(4) bond length is 3.36 Å. The Rb(7)-O(5) bond length is 2.88 Å. The Rb(7)-O(6) bond length is 3.04 Å. The Rb(7)-O(7) bond length is 2.72 Å. In the eighth Rb site, Rb(8) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form RbO4 tetrahedra that share corners with two equivalent Fe(2)O4 tetrahedra and edges with two equivalent Rb(1)O4 tetrahedra. The Rb(8)-O(1) bond length is 2.86 Å. The Rb(8)-O(3) bond length is 2.90 Å. The Rb(8)-O(6) bond length is 2.79 Å. The Rb(8)-O(8) bond length is 2.74 Å. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), one O(4), and one O(5) atom. The Mg(1)-O(2) bond length is 2.05 Å. The Mg(1)-O(3) bond length is 2.23 Å. The Mg(1)-O(4) bond length is 1.92 Å. The Mg(1)-O(5) bond length is 2.03 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(5) atom. The Fe(1)-O(1) bond length is 1.85 Å. The Fe(1)-O(2) bond length is 1.99 Å. The Fe(1)-O(3) bond length is 1.94 Å. The Fe(1)-O(5) bond length is 1.99 Å. In the second Fe site, Fe(2) is bonded to one O(4), one O(6), one O(7), and one O(8) atom to form FeO4 tetrahedra that share corners with two equivalent Rb(1)O4 tetrahedra and corners with two equivalent Rb(8)O4 tetrahedra. The Fe(2)-O(4) bond length is 2.02 Å. The Fe(2)-O(6) bond length is 1.92 Å. The Fe(2)-O(7) bond length is 1.93 Å. The Fe(2)-O(8) bond length is 1.92 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(3), one Rb(5), one Rb(6), one Rb(8), and one Fe(1) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Rb(2), one Rb(4), one Rb(5), one Rb(6), one Rb(7), one Mg(1), and one Fe(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(2), one Rb(5), one Rb(8), one Mg(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Rb(2), one Rb(3), one Rb(5), one Rb(7), one Mg(1), and one Fe(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Rb(2), one Rb(6), one Rb(7), one Mg(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(4), one Rb(7), one Rb(8), and one Fe(2) atom. In the seventh O site, O(7) is bonded in a distorted octahedral geometry to one Rb(2), one Rb(3), one Rb(4), one Rb(5), one Rb(7), and one Fe(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(4), one Rb(6), one Rb(8), and one Fe(2) atom.