Ca5Mg crystallizes in the monoclinic Cm space group. There are five inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 2-coordinate geometry to two equivalent Ca(4) and two equivalent Mg(1) atoms. In the second Ca site, Ca(2) is bonded in a 2-coordinate geometry to two equivalent Ca(4) and two equivalent Mg(1) atoms. In the third Ca site, Ca(3) is bonded in a 2-coordinate geometry to three equivalent Ca(4) and two equivalent Mg(1) atoms. In the fourth Ca site, Ca(4) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(4), three equivalent Ca(3), and three equivalent Ca(5) atoms to form a mixture of distorted face, corner, and edge-sharing CaCa12 cuboctahedra. In the fifth Ca site, Ca(5) is bonded in a 2-coordinate geometry to three equivalent Ca(4) and two equivalent Mg(1) atoms. Mg(1) is bonded in a body-centered cubic geometry to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and two equivalent Ca(5) atoms.
Ca5Mg crystallizes in the monoclinic Cm space group. There are five inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 2-coordinate geometry to two equivalent Ca(4) and two equivalent Mg(1) atoms. Both Ca(1)-Ca(4) bond lengths are 3.79 Å. Both Ca(1)-Mg(1) bond lengths are 3.42 Å. In the second Ca site, Ca(2) is bonded in a 2-coordinate geometry to two equivalent Ca(4) and two equivalent Mg(1) atoms. Both Ca(2)-Ca(4) bond lengths are 3.79 Å. Both Ca(2)-Mg(1) bond lengths are 3.40 Å. In the third Ca site, Ca(3) is bonded in a 2-coordinate geometry to three equivalent Ca(4) and two equivalent Mg(1) atoms. There are two shorter (3.94 Å) and one longer (4.13 Å) Ca(3)-Ca(4) bond length. Both Ca(3)-Mg(1) bond lengths are 3.56 Å. In the fourth Ca site, Ca(4) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(4), three equivalent Ca(3), and three equivalent Ca(5) atoms to form a mixture of distorted face, corner, and edge-sharing CaCa12 cuboctahedra. Both Ca(4)-Ca(4) bond lengths are 4.02 Å. There are two shorter (3.97 Å) and one longer (4.18 Å) Ca(4)-Ca(5) bond length. In the fifth Ca site, Ca(5) is bonded in a 2-coordinate geometry to three equivalent Ca(4) and two equivalent Mg(1) atoms. Both Ca(5)-Mg(1) bond lengths are 3.57 Å. Mg(1) is bonded in a body-centered cubic geometry to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and two equivalent Ca(5) atoms.