MgTi4O8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form distorted MgO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(4)O6 octahedra,  an edgeedge with one Ti(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Ti(3)O6 octahedra, and  a faceface with one Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-42°. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(8), two equivalent O(2), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. In the second Ti site, Ti(2) is bonded to one O(2), one O(7), two equivalent O(1), and two equivalent O(5) atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. In the third Ti site, Ti(3) is bonded to one O(3), one O(6), two equivalent O(4), and two equivalent O(8) atoms to form distorted TiO6 octahedra that share corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(4)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the fourth Ti site, Ti(4) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-49°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Ti(2) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ti(2) and two equivalent Ti(1) atoms. In the third O site, O(3) is bonded to two equivalent Mg(1), one Ti(3), and two equivalent Ti(4) atoms to form OMg2Ti3 square pyramids that share corners with three equivalent O(6)Mg2Ti3 trigonal bipyramids, corners with two equivalent O(4)MgTi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ti3 square pyramids,  an edgeedge with one O(6)Mg2Ti3 trigonal bipyramid, edges with two equivalent O(4)MgTi3 trigonal pyramids, and edges with two equivalent O(8)MgTi3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Mg(1), one Ti(4), and two equivalent Ti(3) atoms to form OMgTi3 trigonal pyramids that share corners with two equivalent O(3)Mg2Ti3 square pyramids, corners with two equivalent O(4)MgTi3 trigonal pyramids, corners with three equivalent O(8)MgTi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ti3 square pyramids, edges with two equivalent O(6)Mg2Ti3 trigonal bipyramids, and  an edgeedge with one O(8)MgTi3 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ti(4) and two equivalent Ti(2) atoms. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Ti(3), and two equivalent Ti(1) atoms to form distorted OMg2Ti3 trigonal bipyramids that share corners with three equivalent O(3)Mg2Ti3 square pyramids, corners with two equivalent O(8)MgTi3 trigonal pyramids,  an edgeedge with one O(3)Mg2Ti3 square pyramid, edges with two equivalent O(6)Mg2Ti3 trigonal bipyramids, edges with two equivalent O(4)MgTi3 trigonal pyramids, and edges with two equivalent O(8)MgTi3 trigonal pyramids. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ti(2) and two equivalent Ti(4) atoms. In the eighth O site, O(8) is bonded to one Mg(1), one Ti(1), and two equivalent Ti(3) atoms to form OMgTi3 trigonal pyramids that share corners with two equivalent O(6)Mg2Ti3 trigonal bipyramids, corners with two equivalent O(8)MgTi3 trigonal pyramids, corners with three equivalent O(4)MgTi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ti3 square pyramids, edges with two equivalent O(6)Mg2Ti3 trigonal bipyramids, and  an edgeedge with one O(4)MgTi3 trigonal pyramid.
MgTi4O8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form distorted MgO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(4)O6 octahedra,  an edgeedge with one Ti(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Ti(3)O6 octahedra, and  a faceface with one Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-42°. The Mg(1)-O(4) bond length is 1.98 Å. The Mg(1)-O(8) bond length is 2.13 Å. Both Mg(1)-O(3) bond lengths are 2.06 Å. Both Mg(1)-O(6) bond lengths are 2.26 Å. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(8), two equivalent O(2), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. The Ti(1)-O(1) bond length is 1.95 Å. The Ti(1)-O(8) bond length is 2.08 Å. Both Ti(1)-O(2) bond lengths are 1.87 Å. Both Ti(1)-O(6) bond lengths are 2.19 Å. In the second Ti site, Ti(2) is bonded to one O(2), one O(7), two equivalent O(1), and two equivalent O(5) atoms to form a mixture of corner and edge-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. The Ti(2)-O(2) bond length is 2.19 Å. The Ti(2)-O(7) bond length is 1.94 Å. Both Ti(2)-O(1) bond lengths are 2.00 Å. Both Ti(2)-O(5) bond lengths are 2.03 Å. In the third Ti site, Ti(3) is bonded to one O(3), one O(6), two equivalent O(4), and two equivalent O(8) atoms to form distorted TiO6 octahedra that share corners with four equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(4)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. The Ti(3)-O(3) bond length is 2.13 Å. The Ti(3)-O(6) bond length is 1.97 Å. Both Ti(3)-O(4) bond lengths are 2.06 Å. Both Ti(3)-O(8) bond lengths are 2.00 Å. In the fourth Ti site, Ti(4) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-49°. The Ti(4)-O(4) bond length is 2.04 Å. The Ti(4)-O(5) bond length is 1.91 Å. Both Ti(4)-O(3) bond lengths are 2.16 Å. Both Ti(4)-O(7) bond lengths are 1.98 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Ti(2) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ti(2) and two equivalent Ti(1) atoms. In the third O site, O(3) is bonded to two equivalent Mg(1), one Ti(3), and two equivalent Ti(4) atoms to form OMg2Ti3 square pyramids that share corners with three equivalent O(6)Mg2Ti3 trigonal bipyramids, corners with two equivalent O(4)MgTi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ti3 square pyramids,  an edgeedge with one O(6)Mg2Ti3 trigonal bipyramid, edges with two equivalent O(4)MgTi3 trigonal pyramids, and edges with two equivalent O(8)MgTi3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Mg(1), one Ti(4), and two equivalent Ti(3) atoms to form OMgTi3 trigonal pyramids that share corners with two equivalent O(3)Mg2Ti3 square pyramids, corners with two equivalent O(4)MgTi3 trigonal pyramids, corners with three equivalent O(8)MgTi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ti3 square pyramids, edges with two equivalent O(6)Mg2Ti3 trigonal bipyramids, and  an edgeedge with one O(8)MgTi3 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ti(4) and two equivalent Ti(2) atoms. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Ti(3), and two equivalent Ti(1) atoms to form distorted OMg2Ti3 trigonal bipyramids that share corners with three equivalent O(3)Mg2Ti3 square pyramids, corners with two equivalent O(8)MgTi3 trigonal pyramids,  an edgeedge with one O(3)Mg2Ti3 square pyramid, edges with two equivalent O(6)Mg2Ti3 trigonal bipyramids, edges with two equivalent O(4)MgTi3 trigonal pyramids, and edges with two equivalent O(8)MgTi3 trigonal pyramids. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ti(2) and two equivalent Ti(4) atoms. In the eighth O site, O(8) is bonded to one Mg(1), one Ti(1), and two equivalent Ti(3) atoms to form OMgTi3 trigonal pyramids that share corners with two equivalent O(6)Mg2Ti3 trigonal bipyramids, corners with two equivalent O(8)MgTi3 trigonal pyramids, corners with three equivalent O(4)MgTi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ti3 square pyramids, edges with two equivalent O(6)Mg2Ti3 trigonal bipyramids, and  an edgeedge with one O(4)MgTi3 trigonal pyramid.