Mg4Ti3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Mg(2), four equivalent Mg(1), and five equivalent Ti(1) atoms to form distorted MgMg7Ti5 cuboctahedra that share corners with three equivalent Mg(2)Mg9Ti3 cuboctahedra, corners with six equivalent Mg(1)Mg7Ti5 cuboctahedra, corners with nine equivalent Ti(1)Mg6Ti6 cuboctahedra,  an edgeedge with one Mg(2)Mg9Ti3 cuboctahedra, edges with six equivalent Mg(1)Mg7Ti5 cuboctahedra, edges with eleven equivalent Ti(1)Mg6Ti6 cuboctahedra, faces with three equivalent Mg(2)Mg9Ti3 cuboctahedra, faces with seven equivalent Ti(1)Mg6Ti6 cuboctahedra, and faces with ten equivalent Mg(1)Mg7Ti5 cuboctahedra. In the second Mg site, Mg(2) is bonded to nine equivalent Mg(1) and three equivalent Ti(1) atoms to form MgMg9Ti3 cuboctahedra that share corners with nine equivalent Mg(1)Mg7Ti5 cuboctahedra, corners with nine equivalent Ti(1)Mg6Ti6 cuboctahedra, edges with three equivalent Mg(1)Mg7Ti5 cuboctahedra, edges with six equivalent Mg(2)Mg9Ti3 cuboctahedra, edges with nine equivalent Ti(1)Mg6Ti6 cuboctahedra, faces with two equivalent Mg(2)Mg9Ti3 cuboctahedra, faces with nine equivalent Mg(1)Mg7Ti5 cuboctahedra, and faces with nine equivalent Ti(1)Mg6Ti6 cuboctahedra. Ti(1) is bonded to one Mg(2), five equivalent Mg(1), and six equivalent Ti(1) atoms to form TiMg6Ti6 cuboctahedra that share corners with three equivalent Mg(2)Mg9Ti3 cuboctahedra, corners with six equivalent Ti(1)Mg6Ti6 cuboctahedra, corners with nine equivalent Mg(1)Mg7Ti5 cuboctahedra, edges with three equivalent Mg(2)Mg9Ti3 cuboctahedra, edges with four equivalent Ti(1)Mg6Ti6 cuboctahedra, edges with eleven equivalent Mg(1)Mg7Ti5 cuboctahedra, faces with three equivalent Mg(2)Mg9Ti3 cuboctahedra, faces with seven equivalent Mg(1)Mg7Ti5 cuboctahedra, and faces with ten equivalent Ti(1)Mg6Ti6 cuboctahedra.
Mg4Ti3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Mg(2), four equivalent Mg(1), and five equivalent Ti(1) atoms to form distorted MgMg7Ti5 cuboctahedra that share corners with three equivalent Mg(2)Mg9Ti3 cuboctahedra, corners with six equivalent Mg(1)Mg7Ti5 cuboctahedra, corners with nine equivalent Ti(1)Mg6Ti6 cuboctahedra,  an edgeedge with one Mg(2)Mg9Ti3 cuboctahedra, edges with six equivalent Mg(1)Mg7Ti5 cuboctahedra, edges with eleven equivalent Ti(1)Mg6Ti6 cuboctahedra, faces with three equivalent Mg(2)Mg9Ti3 cuboctahedra, faces with seven equivalent Ti(1)Mg6Ti6 cuboctahedra, and faces with ten equivalent Mg(1)Mg7Ti5 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.07 Å. There are two shorter (3.06 Å) and two longer (3.22 Å) Mg(1)-Mg(1) bond lengths. There are a spread of Mg(1)-Ti(1) bond distances ranging from 3.02-3.32 Å. In the second Mg site, Mg(2) is bonded to nine equivalent Mg(1) and three equivalent Ti(1) atoms to form MgMg9Ti3 cuboctahedra that share corners with nine equivalent Mg(1)Mg7Ti5 cuboctahedra, corners with nine equivalent Ti(1)Mg6Ti6 cuboctahedra, edges with three equivalent Mg(1)Mg7Ti5 cuboctahedra, edges with six equivalent Mg(2)Mg9Ti3 cuboctahedra, edges with nine equivalent Ti(1)Mg6Ti6 cuboctahedra, faces with two equivalent Mg(2)Mg9Ti3 cuboctahedra, faces with nine equivalent Mg(1)Mg7Ti5 cuboctahedra, and faces with nine equivalent Ti(1)Mg6Ti6 cuboctahedra. All Mg(2)-Ti(1) bond lengths are 3.27 Å. Ti(1) is bonded to one Mg(2), five equivalent Mg(1), and six equivalent Ti(1) atoms to form TiMg6Ti6 cuboctahedra that share corners with three equivalent Mg(2)Mg9Ti3 cuboctahedra, corners with six equivalent Ti(1)Mg6Ti6 cuboctahedra, corners with nine equivalent Mg(1)Mg7Ti5 cuboctahedra, edges with three equivalent Mg(2)Mg9Ti3 cuboctahedra, edges with four equivalent Ti(1)Mg6Ti6 cuboctahedra, edges with eleven equivalent Mg(1)Mg7Ti5 cuboctahedra, faces with three equivalent Mg(2)Mg9Ti3 cuboctahedra, faces with seven equivalent Mg(1)Mg7Ti5 cuboctahedra, and faces with ten equivalent Ti(1)Mg6Ti6 cuboctahedra. There are two shorter (2.77 Å) and four longer (2.92 Å) Ti(1)-Ti(1) bond lengths.