Mg2Ti3O8 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Ti(1)O6 octahedra, corners with three equivalent Mg(2)O4 tetrahedra, and edges with three equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the second Mg site, Mg(2) is bonded to one O(4) and three equivalent O(2) atoms to form MgO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with nine equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-63°. Ti(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form TiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with four equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and two equivalent Ti(1) atoms to form distorted OMg2Ti2 tetrahedra that share corners with two equivalent O(2)Mg2Ti2 tetrahedra,  a cornercorner with one O(4)MgTi3 trigonal pyramid, edges with two equivalent O(2)Mg2Ti2 tetrahedra, and  an edgeedge with one O(4)MgTi3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Ti(1) atoms. In the fourth O site, O(4) is bonded to one Mg(2) and three equivalent Ti(1) atoms to form a mixture of distorted edge and corner-sharing OMgTi3 trigonal pyramids.
Mg2Ti3O8 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Ti(1)O6 octahedra, corners with three equivalent Mg(2)O4 tetrahedra, and edges with three equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Mg(1)-O(1) bond lengths are 2.11 Å. All Mg(1)-O(2) bond lengths are 2.13 Å. In the second Mg site, Mg(2) is bonded to one O(4) and three equivalent O(2) atoms to form MgO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with nine equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-63°. The Mg(2)-O(4) bond length is 2.03 Å. All Mg(2)-O(2) bond lengths are 1.98 Å. Ti(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form TiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with four equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. The Ti(1)-O(3) bond length is 1.96 Å. The Ti(1)-O(4) bond length is 2.06 Å. Both Ti(1)-O(1) bond lengths are 1.93 Å. Both Ti(1)-O(2) bond lengths are 2.02 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and two equivalent Ti(1) atoms to form distorted OMg2Ti2 tetrahedra that share corners with two equivalent O(2)Mg2Ti2 tetrahedra,  a cornercorner with one O(4)MgTi3 trigonal pyramid, edges with two equivalent O(2)Mg2Ti2 tetrahedra, and  an edgeedge with one O(4)MgTi3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Ti(1) atoms. In the fourth O site, O(4) is bonded to one Mg(2) and three equivalent Ti(1) atoms to form a mixture of distorted edge and corner-sharing OMgTi3 trigonal pyramids.