MgTi4O8 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Ti(2)O6 pentagonal pyramids and edges with two equivalent Ti(2)O6 pentagonal pyramids. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second Ti site, Ti(2) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form distorted TiO6 pentagonal pyramids that share corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(2)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 19-70°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to one Mg(1), one Ti(2), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to two equivalent Ti(1) and two equivalent Ti(2) atoms to form distorted OTi4 tetrahedra that share  a cornercorner with one O(3)MgTi3 trigonal pyramid, edges with two equivalent O(2)Ti4 tetrahedra,  an edgeedge with one O(3)MgTi3 trigonal pyramid, and  a faceface with one O(3)MgTi3 trigonal pyramid. In the third O site, O(3) is bonded to one Mg(1), one Ti(2), and two equivalent Ti(1) atoms to form distorted OMgTi3 trigonal pyramids that share  a cornercorner with one O(2)Ti4 tetrahedra,  a cornercorner with one O(3)MgTi3 trigonal pyramid,  an edgeedge with one O(2)Ti4 tetrahedra,  an edgeedge with one O(3)MgTi3 trigonal pyramid, and  a faceface with one O(2)Ti4 tetrahedra. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Ti(1), and two equivalent Ti(2) atoms.
MgTi4O8 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Ti(2)O6 pentagonal pyramids and edges with two equivalent Ti(2)O6 pentagonal pyramids. Both Mg(1)-O(1) bond lengths are 2.16 Å. Both Mg(1)-O(3) bond lengths are 2.02 Å. Both Mg(1)-O(4) bond lengths are 2.12 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. The Ti(1)-O(4) bond length is 1.98 Å. There is one shorter (2.09 Å) and one longer (2.11 Å) Ti(1)-O(1) bond length. There is one shorter (2.08 Å) and one longer (2.12 Å) Ti(1)-O(2) bond length. There is one shorter (2.05 Å) and one longer (2.22 Å) Ti(1)-O(3) bond length. In the second Ti site, Ti(2) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form distorted TiO6 pentagonal pyramids that share corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(2)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 19-70°. The Ti(2)-O(1) bond length is 1.95 Å. The Ti(2)-O(3) bond length is 1.91 Å. There is one shorter (1.96 Å) and one longer (2.11 Å) Ti(2)-O(2) bond length. There is one shorter (1.98 Å) and one longer (2.20 Å) Ti(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to one Mg(1), one Ti(2), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to two equivalent Ti(1) and two equivalent Ti(2) atoms to form distorted OTi4 tetrahedra that share  a cornercorner with one O(3)MgTi3 trigonal pyramid, edges with two equivalent O(2)Ti4 tetrahedra,  an edgeedge with one O(3)MgTi3 trigonal pyramid, and  a faceface with one O(3)MgTi3 trigonal pyramid. In the third O site, O(3) is bonded to one Mg(1), one Ti(2), and two equivalent Ti(1) atoms to form distorted OMgTi3 trigonal pyramids that share  a cornercorner with one O(2)Ti4 tetrahedra,  a cornercorner with one O(3)MgTi3 trigonal pyramid,  an edgeedge with one O(2)Ti4 tetrahedra,  an edgeedge with one O(3)MgTi3 trigonal pyramid, and  a faceface with one O(2)Ti4 tetrahedra. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Ti(1), and two equivalent Ti(2) atoms.