MgTa3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. Mg(1) is bonded to four equivalent Ta(1) and eight equivalent Ta(2) atoms to form MgTa12 cuboctahedra that share corners with four equivalent Mg(1)Ta12 cuboctahedra, corners with eight equivalent Ta(1)Mg4Ta8 cuboctahedra, edges with eight equivalent Mg(1)Ta12 cuboctahedra, edges with sixteen equivalent Ta(2)Mg4Ta8 cuboctahedra, faces with four equivalent Mg(1)Ta12 cuboctahedra, faces with six equivalent Ta(1)Mg4Ta8 cuboctahedra, and faces with eight equivalent Ta(2)Mg4Ta8 cuboctahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to four equivalent Mg(1) and eight equivalent Ta(2) atoms to form TaMg4Ta8 cuboctahedra that share corners with four equivalent Ta(1)Mg4Ta8 cuboctahedra, corners with eight equivalent Mg(1)Ta12 cuboctahedra, edges with eight equivalent Ta(1)Mg4Ta8 cuboctahedra, edges with sixteen equivalent Ta(2)Mg4Ta8 cuboctahedra, faces with four equivalent Ta(1)Mg4Ta8 cuboctahedra, faces with six equivalent Mg(1)Ta12 cuboctahedra, and faces with eight equivalent Ta(2)Mg4Ta8 cuboctahedra. In the second Ta site, Ta(2) is bonded to four equivalent Mg(1), four equivalent Ta(1), and four equivalent Ta(2) atoms to form distorted TaMg4Ta8 cuboctahedra that share corners with twelve equivalent Ta(2)Mg4Ta8 cuboctahedra, edges with eight equivalent Mg(1)Ta12 cuboctahedra, edges with eight equivalent Ta(1)Mg4Ta8 cuboctahedra, edges with eight equivalent Ta(2)Mg4Ta8 cuboctahedra, faces with four equivalent Mg(1)Ta12 cuboctahedra, faces with four equivalent Ta(1)Mg4Ta8 cuboctahedra, and faces with ten equivalent Ta(2)Mg4Ta8 cuboctahedra.
MgTa3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. Mg(1) is bonded to four equivalent Ta(1) and eight equivalent Ta(2) atoms to form MgTa12 cuboctahedra that share corners with four equivalent Mg(1)Ta12 cuboctahedra, corners with eight equivalent Ta(1)Mg4Ta8 cuboctahedra, edges with eight equivalent Mg(1)Ta12 cuboctahedra, edges with sixteen equivalent Ta(2)Mg4Ta8 cuboctahedra, faces with four equivalent Mg(1)Ta12 cuboctahedra, faces with six equivalent Ta(1)Mg4Ta8 cuboctahedra, and faces with eight equivalent Ta(2)Mg4Ta8 cuboctahedra. All Mg(1)-Ta(1) bond lengths are 3.03 Å. All Mg(1)-Ta(2) bond lengths are 2.95 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to four equivalent Mg(1) and eight equivalent Ta(2) atoms to form TaMg4Ta8 cuboctahedra that share corners with four equivalent Ta(1)Mg4Ta8 cuboctahedra, corners with eight equivalent Mg(1)Ta12 cuboctahedra, edges with eight equivalent Ta(1)Mg4Ta8 cuboctahedra, edges with sixteen equivalent Ta(2)Mg4Ta8 cuboctahedra, faces with four equivalent Ta(1)Mg4Ta8 cuboctahedra, faces with six equivalent Mg(1)Ta12 cuboctahedra, and faces with eight equivalent Ta(2)Mg4Ta8 cuboctahedra. All Ta(1)-Ta(2) bond lengths are 2.95 Å. In the second Ta site, Ta(2) is bonded to four equivalent Mg(1), four equivalent Ta(1), and four equivalent Ta(2) atoms to form distorted TaMg4Ta8 cuboctahedra that share corners with twelve equivalent Ta(2)Mg4Ta8 cuboctahedra, edges with eight equivalent Mg(1)Ta12 cuboctahedra, edges with eight equivalent Ta(1)Mg4Ta8 cuboctahedra, edges with eight equivalent Ta(2)Mg4Ta8 cuboctahedra, faces with four equivalent Mg(1)Ta12 cuboctahedra, faces with four equivalent Ta(1)Mg4Ta8 cuboctahedra, and faces with ten equivalent Ta(2)Mg4Ta8 cuboctahedra. All Ta(2)-Ta(2) bond lengths are 3.03 Å.