CsMgFe(MoO4)2 crystallizes in the triclinic P1 space group. Cs(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), three equivalent O(1), and three equivalent O(2) atoms to form distorted CsO12 cuboctahedra that share edges with six equivalent Cs(1)O12 cuboctahedra, edges with three equivalent Mg(1)O4 tetrahedra, edges with three equivalent Mo(1)O4 tetrahedra, edges with three equivalent Mo(2)O4 tetrahedra, and faces with two equivalent Fe(1)O6 octahedra. Mg(1) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form MgO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra,  a cornercorner with one Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 55-59°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form MoO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 32-33°. In the second Mo site, Mo(2) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form MoO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Mg(1)O4 tetrahedra, and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 56°. Fe(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and faces with two equivalent Cs(1)O12 cuboctahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to three equivalent Cs(1), one Mg(1), and one Mo(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one Mo(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Mo(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Mo(1), and one Fe(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Cs(1), one Mo(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Cs(1), one Mg(1), one Mo(2), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Cs(1), one Mg(1), one Mo(2), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Cs(1), one Mg(1), one Mo(2), and one Fe(1) atom.
CsMgFe(MoO4)2 crystallizes in the triclinic P1 space group. Cs(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), three equivalent O(1), and three equivalent O(2) atoms to form distorted CsO12 cuboctahedra that share edges with six equivalent Cs(1)O12 cuboctahedra, edges with three equivalent Mg(1)O4 tetrahedra, edges with three equivalent Mo(1)O4 tetrahedra, edges with three equivalent Mo(2)O4 tetrahedra, and faces with two equivalent Fe(1)O6 octahedra. The Cs(1)-O(3) bond length is 3.06 Å. The Cs(1)-O(4) bond length is 3.03 Å. The Cs(1)-O(5) bond length is 3.03 Å. The Cs(1)-O(6) bond length is 3.18 Å. The Cs(1)-O(7) bond length is 3.23 Å. The Cs(1)-O(8) bond length is 3.27 Å. There are a spread of Cs(1)-O(1) bond distances ranging from 3.24-3.29 Å. There are a spread of Cs(1)-O(2) bond distances ranging from 3.09-3.51 Å. Mg(1) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form MgO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra,  a cornercorner with one Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 55-59°. The Mg(1)-O(1) bond length is 2.05 Å. The Mg(1)-O(6) bond length is 2.01 Å. The Mg(1)-O(7) bond length is 2.01 Å. The Mg(1)-O(8) bond length is 2.01 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form MoO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 32-33°. The Mo(1)-O(1) bond length is 1.84 Å. The Mo(1)-O(3) bond length is 1.80 Å. The Mo(1)-O(4) bond length is 1.78 Å. The Mo(1)-O(5) bond length is 1.78 Å. In the second Mo site, Mo(2) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form MoO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Mg(1)O4 tetrahedra, and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 56°. The Mo(2)-O(2) bond length is 1.77 Å. The Mo(2)-O(6) bond length is 1.94 Å. The Mo(2)-O(7) bond length is 1.90 Å. The Mo(2)-O(8) bond length is 1.92 Å. Fe(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and faces with two equivalent Cs(1)O12 cuboctahedra. The Fe(1)-O(3) bond length is 2.10 Å. The Fe(1)-O(4) bond length is 2.17 Å. The Fe(1)-O(5) bond length is 2.18 Å. The Fe(1)-O(6) bond length is 2.15 Å. The Fe(1)-O(7) bond length is 2.38 Å. The Fe(1)-O(8) bond length is 2.27 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to three equivalent Cs(1), one Mg(1), and one Mo(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one Mo(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Mo(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Mo(1), and one Fe(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Cs(1), one Mo(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Cs(1), one Mg(1), one Mo(2), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Cs(1), one Mg(1), one Mo(2), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Cs(1), one Mg(1), one Mo(2), and one Fe(1) atom.