MgTm4Co crystallizes in the cubic F-43m space group. Mg(1) is bonded to three equivalent Mg(1), three equivalent Tm(1), three equivalent Tm(2), and three equivalent Tm(3) atoms to form a mixture of face and corner-sharing MgTm9Mg3 cuboctahedra. There are three inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 3-coordinate geometry to three equivalent Mg(1), three equivalent Tm(3), and three equivalent Co(1) atoms. In the second Tm site, Tm(2) is bonded in a bent 150 degrees geometry to two equivalent Mg(1), four equivalent Tm(3), and two equivalent Co(1) atoms. In the third Tm site, Tm(3) is bonded in a 14-coordinate geometry to two equivalent Mg(1), two equivalent Tm(1), four equivalent Tm(2), four equivalent Tm(3), and two equivalent Co(1) atoms. Co(1) is bonded in a 6-coordinate geometry to three equivalent Tm(1), three equivalent Tm(2), and three equivalent Tm(3) atoms.
MgTm4Co crystallizes in the cubic F-43m space group. Mg(1) is bonded to three equivalent Mg(1), three equivalent Tm(1), three equivalent Tm(2), and three equivalent Tm(3) atoms to form a mixture of face and corner-sharing MgTm9Mg3 cuboctahedra. All Mg(1)-Mg(1) bond lengths are 2.96 Å. All Mg(1)-Tm(1) bond lengths are 3.46 Å. All Mg(1)-Tm(2) bond lengths are 3.46 Å. All Mg(1)-Tm(3) bond lengths are 3.24 Å. There are three inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 3-coordinate geometry to three equivalent Mg(1), three equivalent Tm(3), and three equivalent Co(1) atoms. All Tm(1)-Tm(3) bond lengths are 3.40 Å. All Tm(1)-Co(1) bond lengths are 2.72 Å. In the second Tm site, Tm(2) is bonded in a bent 150 degrees geometry to two equivalent Mg(1), four equivalent Tm(3), and two equivalent Co(1) atoms. All Tm(2)-Tm(3) bond lengths are 3.53 Å. Both Tm(2)-Co(1) bond lengths are 2.71 Å. In the third Tm site, Tm(3) is bonded in a 14-coordinate geometry to two equivalent Mg(1), two equivalent Tm(1), four equivalent Tm(2), four equivalent Tm(3), and two equivalent Co(1) atoms. All Tm(3)-Tm(3) bond lengths are 3.54 Å. Both Tm(3)-Co(1) bond lengths are 3.39 Å. Co(1) is bonded in a 6-coordinate geometry to three equivalent Tm(1), three equivalent Tm(2), and three equivalent Tm(3) atoms.