MgTi4(FeO5)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with two equivalent Ti(1)O5 trigonal bipyramids, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, and edges with four equivalent Ti(1)O5 trigonal bipyramids. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(4), one O(5), and three equivalent O(2) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, corners with three equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-65°. In the second Ti site, Ti(2) is bonded to one O(4), two equivalent O(3), and three equivalent O(1) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Fe(1)O5 trigonal bipyramid, edges with three equivalent Ti(2)O6 octahedra, and edges with three equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 40°. Fe(1) is bonded to one O(1), one O(3), one O(5), and two equivalent O(4) atoms to form FeO5 trigonal bipyramids that share  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, corners with three equivalent Ti(1)O5 trigonal bipyramids, and edges with three equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-63°. There are five inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ti(2) and one Fe(1) atom to form distorted OTi3Fe trigonal pyramids that share  a cornercorner with one O(4)Ti2Fe2 tetrahedra,  a cornercorner with one O(5)Mg2TiFe trigonal pyramid, corners with two equivalent O(1)Ti3Fe trigonal pyramids, edges with two equivalent O(4)Ti2Fe2 tetrahedra, and edges with two equivalent O(1)Ti3Fe trigonal pyramids. In the second O site, O(2) is bonded to one Mg(1) and three equivalent Ti(1) atoms to form OMgTi3 tetrahedra that share corners with three equivalent O(2)MgTi3 tetrahedra, corners with three equivalent O(4)Ti2Fe2 tetrahedra, corners with three equivalent O(5)Mg2TiFe trigonal pyramids, edges with two equivalent O(2)MgTi3 tetrahedra, and edges with two equivalent O(5)Mg2TiFe trigonal pyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Ti(2) and one Fe(1) atom. In the fourth O site, O(4) is bonded to one Ti(1), one Ti(2), and two equivalent Fe(1) atoms to form distorted OTi2Fe2 tetrahedra that share corners with two equivalent O(4)Ti2Fe2 tetrahedra, corners with three equivalent O(2)MgTi3 tetrahedra,  a cornercorner with one O(1)Ti3Fe trigonal pyramid, corners with three equivalent O(5)Mg2TiFe trigonal pyramids, and edges with two equivalent O(1)Ti3Fe trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Ti(1), and one Fe(1) atom to form distorted OMg2TiFe trigonal pyramids that share corners with three equivalent O(2)MgTi3 tetrahedra, corners with three equivalent O(4)Ti2Fe2 tetrahedra,  a cornercorner with one O(1)Ti3Fe trigonal pyramid, corners with four equivalent O(5)Mg2TiFe trigonal pyramids, edges with two equivalent O(2)MgTi3 tetrahedra, and  an edgeedge with one O(5)Mg2TiFe trigonal pyramid.
MgTi4(FeO5)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with two equivalent Ti(1)O5 trigonal bipyramids, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, and edges with four equivalent Ti(1)O5 trigonal bipyramids. Both Mg(1)-O(2) bond lengths are 2.01 Å. All Mg(1)-O(5) bond lengths are 2.26 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(4), one O(5), and three equivalent O(2) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, corners with three equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-65°. The Ti(1)-O(4) bond length is 1.86 Å. The Ti(1)-O(5) bond length is 1.90 Å. There are two shorter (1.98 Å) and one longer (2.08 Å) Ti(1)-O(2) bond length. In the second Ti site, Ti(2) is bonded to one O(4), two equivalent O(3), and three equivalent O(1) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Fe(1)O5 trigonal bipyramid, edges with three equivalent Ti(2)O6 octahedra, and edges with three equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 40°. The Ti(2)-O(4) bond length is 2.28 Å. There is one shorter (1.90 Å) and one longer (1.96 Å) Ti(2)-O(3) bond length. There are two shorter (1.95 Å) and one longer (2.28 Å) Ti(2)-O(1) bond length. Fe(1) is bonded to one O(1), one O(3), one O(5), and two equivalent O(4) atoms to form FeO5 trigonal bipyramids that share  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, corners with three equivalent Ti(1)O5 trigonal bipyramids, and edges with three equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-63°. The Fe(1)-O(1) bond length is 2.16 Å. The Fe(1)-O(3) bond length is 2.04 Å. The Fe(1)-O(5) bond length is 2.03 Å. Both Fe(1)-O(4) bond lengths are 2.18 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ti(2) and one Fe(1) atom to form distorted OTi3Fe trigonal pyramids that share  a cornercorner with one O(4)Ti2Fe2 tetrahedra,  a cornercorner with one O(5)Mg2TiFe trigonal pyramid, corners with two equivalent O(1)Ti3Fe trigonal pyramids, edges with two equivalent O(4)Ti2Fe2 tetrahedra, and edges with two equivalent O(1)Ti3Fe trigonal pyramids. In the second O site, O(2) is bonded to one Mg(1) and three equivalent Ti(1) atoms to form OMgTi3 tetrahedra that share corners with three equivalent O(2)MgTi3 tetrahedra, corners with three equivalent O(4)Ti2Fe2 tetrahedra, corners with three equivalent O(5)Mg2TiFe trigonal pyramids, edges with two equivalent O(2)MgTi3 tetrahedra, and edges with two equivalent O(5)Mg2TiFe trigonal pyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Ti(2) and one Fe(1) atom. In the fourth O site, O(4) is bonded to one Ti(1), one Ti(2), and two equivalent Fe(1) atoms to form distorted OTi2Fe2 tetrahedra that share corners with two equivalent O(4)Ti2Fe2 tetrahedra, corners with three equivalent O(2)MgTi3 tetrahedra,  a cornercorner with one O(1)Ti3Fe trigonal pyramid, corners with three equivalent O(5)Mg2TiFe trigonal pyramids, and edges with two equivalent O(1)Ti3Fe trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Ti(1), and one Fe(1) atom to form distorted OMg2TiFe trigonal pyramids that share corners with three equivalent O(2)MgTi3 tetrahedra, corners with three equivalent O(4)Ti2Fe2 tetrahedra,  a cornercorner with one O(1)Ti3Fe trigonal pyramid, corners with four equivalent O(5)Mg2TiFe trigonal pyramids, edges with two equivalent O(2)MgTi3 tetrahedra, and  an edgeedge with one O(5)Mg2TiFe trigonal pyramid.