Ca2Mg crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent Ca(2), four equivalent Ca(1), and six equivalent Mg(1) atoms to form distorted CaCa6Mg6 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with six equivalent Ca(2)Ca8Mg4 cuboctahedra, edges with eleven equivalent Ca(2)Ca8Mg4 cuboctahedra, faces with four equivalent Ca(2)Ca8Mg4 cuboctahedra, and faces with ten equivalent Ca(1)Ca6Mg6 cuboctahedra. In the second Ca site, Ca(2) is bonded to two equivalent Ca(1), six equivalent Ca(2), and four equivalent Mg(1) atoms to form distorted CaCa8Mg4 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with six equivalent Ca(2)Ca8Mg4 cuboctahedra, edges with four equivalent Ca(2)Ca8Mg4 cuboctahedra, edges with eleven equivalent Ca(1)Ca6Mg6 cuboctahedra, faces with four equivalent Ca(1)Ca6Mg6 cuboctahedra, and faces with eight equivalent Ca(2)Ca8Mg4 cuboctahedra. Mg(1) is bonded in a 10-coordinate geometry to four equivalent Ca(2) and six equivalent Ca(1) atoms.
Ca2Mg crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent Ca(2), four equivalent Ca(1), and six equivalent Mg(1) atoms to form distorted CaCa6Mg6 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with six equivalent Ca(2)Ca8Mg4 cuboctahedra, edges with eleven equivalent Ca(2)Ca8Mg4 cuboctahedra, faces with four equivalent Ca(2)Ca8Mg4 cuboctahedra, and faces with ten equivalent Ca(1)Ca6Mg6 cuboctahedra. Both Ca(1)-Ca(2) bond lengths are 3.75 Å. There are two shorter (3.61 Å) and two longer (3.75 Å) Ca(1)-Ca(1) bond lengths. There are two shorter (3.59 Å) and four longer (3.68 Å) Ca(1)-Mg(1) bond lengths. In the second Ca site, Ca(2) is bonded to two equivalent Ca(1), six equivalent Ca(2), and four equivalent Mg(1) atoms to form distorted CaCa8Mg4 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with six equivalent Ca(2)Ca8Mg4 cuboctahedra, edges with four equivalent Ca(2)Ca8Mg4 cuboctahedra, edges with eleven equivalent Ca(1)Ca6Mg6 cuboctahedra, faces with four equivalent Ca(1)Ca6Mg6 cuboctahedra, and faces with eight equivalent Ca(2)Ca8Mg4 cuboctahedra. There are four shorter (3.62 Å) and two longer (3.75 Å) Ca(2)-Ca(2) bond lengths. There are two shorter (3.52 Å) and two longer (3.71 Å) Ca(2)-Mg(1) bond lengths. Mg(1) is bonded in a 10-coordinate geometry to four equivalent Ca(2) and six equivalent Ca(1) atoms.