MgTi4O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Ti(2)O5 trigonal bipyramid,  a cornercorner with one Ti(3)O5 trigonal bipyramid,  a cornercorner with one Ti(4)O5 trigonal bipyramid, edges with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Ti(1)O5 trigonal bipyramid,  an edgeedge with one Ti(2)O5 trigonal bipyramid,  an edgeedge with one Ti(3)O5 trigonal bipyramid, and  an edgeedge with one Ti(4)O5 trigonal bipyramid. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), one O(7), and two equivalent O(5) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(2)O5 trigonal bipyramid,  a cornercorner with one Ti(3)O5 trigonal bipyramid, corners with two equivalent Ti(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 69°. In the second Ti site, Ti(2) is bonded to one O(3), one O(4), one O(8), and two equivalent O(6) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Ti(4)O5 trigonal bipyramid, corners with two equivalent Ti(2)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 80°. In the third Ti site, Ti(3) is bonded to one O(1), one O(2), one O(6), and two equivalent O(8) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Ti(4)O5 trigonal bipyramid, corners with two equivalent Ti(3)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 80°. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(3), one O(5), and two equivalent O(7) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(2)O5 trigonal bipyramid,  a cornercorner with one Ti(3)O5 trigonal bipyramid, corners with two equivalent Ti(4)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Ti(3), and one Ti(4) atom to form a mixture of corner and edge-sharing OMg2Ti2 trigonal pyramids. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Ti(1), and one Ti(3) atom. In the third O site, O(3) is bonded in a T-shaped geometry to one Mg(1), one Ti(2), and one Ti(4) atom. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Ti(1), and one Ti(2) atom to form a mixture of corner and edge-sharing OMg2Ti2 trigonal pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ti(4) and two equivalent Ti(1) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Ti(3) and two equivalent Ti(2) atoms. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Ti(4) atoms. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Ti(2) and two equivalent Ti(3) atoms.
MgTi4O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Ti(2)O5 trigonal bipyramid,  a cornercorner with one Ti(3)O5 trigonal bipyramid,  a cornercorner with one Ti(4)O5 trigonal bipyramid, edges with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Ti(1)O5 trigonal bipyramid,  an edgeedge with one Ti(2)O5 trigonal bipyramid,  an edgeedge with one Ti(3)O5 trigonal bipyramid, and  an edgeedge with one Ti(4)O5 trigonal bipyramid. The Mg(1)-O(2) bond length is 2.09 Å. The Mg(1)-O(3) bond length is 2.09 Å. There is one shorter (2.15 Å) and one longer (2.19 Å) Mg(1)-O(1) bond length. There is one shorter (2.15 Å) and one longer (2.21 Å) Mg(1)-O(4) bond length. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), one O(7), and two equivalent O(5) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(2)O5 trigonal bipyramid,  a cornercorner with one Ti(3)O5 trigonal bipyramid, corners with two equivalent Ti(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 69°. The Ti(1)-O(2) bond length is 1.98 Å. The Ti(1)-O(4) bond length is 1.94 Å. The Ti(1)-O(7) bond length is 2.09 Å. There is one shorter (1.88 Å) and one longer (1.94 Å) Ti(1)-O(5) bond length. In the second Ti site, Ti(2) is bonded to one O(3), one O(4), one O(8), and two equivalent O(6) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Ti(4)O5 trigonal bipyramid, corners with two equivalent Ti(2)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 80°. The Ti(2)-O(3) bond length is 1.89 Å. The Ti(2)-O(4) bond length is 2.02 Å. The Ti(2)-O(8) bond length is 2.07 Å. There is one shorter (1.86 Å) and one longer (1.97 Å) Ti(2)-O(6) bond length. In the third Ti site, Ti(3) is bonded to one O(1), one O(2), one O(6), and two equivalent O(8) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  a cornercorner with one Ti(4)O5 trigonal bipyramid, corners with two equivalent Ti(3)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 80°. The Ti(3)-O(1) bond length is 2.01 Å. The Ti(3)-O(2) bond length is 1.89 Å. The Ti(3)-O(6) bond length is 2.09 Å. There is one shorter (1.87 Å) and one longer (1.98 Å) Ti(3)-O(8) bond length. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(3), one O(5), and two equivalent O(7) atoms to form TiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Ti(2)O5 trigonal bipyramid,  a cornercorner with one Ti(3)O5 trigonal bipyramid, corners with two equivalent Ti(4)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°. The Ti(4)-O(1) bond length is 1.95 Å. The Ti(4)-O(3) bond length is 1.98 Å. The Ti(4)-O(5) bond length is 2.10 Å. There is one shorter (1.88 Å) and one longer (1.94 Å) Ti(4)-O(7) bond length. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Ti(3), and one Ti(4) atom to form a mixture of corner and edge-sharing OMg2Ti2 trigonal pyramids. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Ti(1), and one Ti(3) atom. In the third O site, O(3) is bonded in a T-shaped geometry to one Mg(1), one Ti(2), and one Ti(4) atom. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Ti(1), and one Ti(2) atom to form a mixture of corner and edge-sharing OMg2Ti2 trigonal pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ti(4) and two equivalent Ti(1) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Ti(3) and two equivalent Ti(2) atoms. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Ti(4) atoms. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Ti(2) and two equivalent Ti(3) atoms.