Mg3Fe4(MoO4)6 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Mg site, Mg(2) is bonded to one O(11), one O(2), one O(5), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share  a cornercorner with one Mo(2)O4 tetrahedra, corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(10), one O(11), one O(3), and one O(6) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 19-68°. In the second Mo site, Mo(2) is bonded to one O(1), one O(4), one O(7), and one O(8) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, and  a cornercorner with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 45-55°. In the third Mo site, Mo(3) is bonded to one O(12), one O(2), one O(5), and one O(9) atom to form MoO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 19-55°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(6), one O(7), one O(9), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Mo(3)O4 tetrahedra, corners with two equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(12), one O(5), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Mg(2) and one Mo(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Mo(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mo(2) and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mo(3), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mg(2), one Mo(1), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Mg(2), one Mo(2), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Mo(2) and two equivalent Fe(2) atoms. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Mo(3) and one Fe(1) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Mo(1) and one Fe(2) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mo(1), and one Fe(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Mo(3) and one Fe(2) atom.
Mg3Fe4(MoO4)6 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Mg(1)-O(1) bond lengths are 1.96 Å. Both Mg(1)-O(3) bond lengths are 2.14 Å. In the second Mg site, Mg(2) is bonded to one O(11), one O(2), one O(5), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share  a cornercorner with one Mo(2)O4 tetrahedra, corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The Mg(2)-O(11) bond length is 2.14 Å. The Mg(2)-O(2) bond length is 2.02 Å. The Mg(2)-O(5) bond length is 2.05 Å. The Mg(2)-O(6) bond length is 2.08 Å. The Mg(2)-O(7) bond length is 1.99 Å. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(10), one O(11), one O(3), and one O(6) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 19-68°. The Mo(1)-O(10) bond length is 1.76 Å. The Mo(1)-O(11) bond length is 1.83 Å. The Mo(1)-O(3) bond length is 1.81 Å. The Mo(1)-O(6) bond length is 1.82 Å. In the second Mo site, Mo(2) is bonded to one O(1), one O(4), one O(7), and one O(8) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, and  a cornercorner with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 45-55°. The Mo(2)-O(1) bond length is 1.81 Å. The Mo(2)-O(4) bond length is 1.91 Å. The Mo(2)-O(7) bond length is 1.91 Å. The Mo(2)-O(8) bond length is 1.87 Å. In the third Mo site, Mo(3) is bonded to one O(12), one O(2), one O(5), and one O(9) atom to form MoO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 19-55°. The Mo(3)-O(12) bond length is 1.76 Å. The Mo(3)-O(2) bond length is 1.81 Å. The Mo(3)-O(5) bond length is 1.85 Å. The Mo(3)-O(9) bond length is 1.77 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(6), one O(7), one O(9), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Mo(3)O4 tetrahedra, corners with two equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The Fe(1)-O(3) bond length is 2.41 Å. The Fe(1)-O(6) bond length is 2.31 Å. The Fe(1)-O(7) bond length is 2.05 Å. The Fe(1)-O(9) bond length is 2.10 Å. There is one shorter (2.07 Å) and one longer (2.15 Å) Fe(1)-O(4) bond length. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(12), one O(5), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The Fe(2)-O(10) bond length is 2.14 Å. The Fe(2)-O(11) bond length is 2.14 Å. The Fe(2)-O(12) bond length is 2.09 Å. The Fe(2)-O(5) bond length is 2.21 Å. There is one shorter (2.09 Å) and one longer (2.12 Å) Fe(2)-O(8) bond length. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Mg(2) and one Mo(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Mo(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mo(2) and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mo(3), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mg(2), one Mo(1), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Mg(2), one Mo(2), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Mo(2) and two equivalent Fe(2) atoms. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Mo(3) and one Fe(1) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Mo(1) and one Fe(2) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mo(1), and one Fe(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Mo(3) and one Fe(2) atom.