Mg6AlC crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Al(1), and two equivalent C(1) atoms. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Al(1) atoms to form a mixture of distorted face and corner-sharing MgMg10Al2 cuboctahedra. In the third Mg site, Mg(3) is bonded in a 2-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Al(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to two equivalent Mg(2) and four equivalent Mg(1) atoms. Al(1) is bonded in a distorted q6 geometry to two equivalent Mg(2), four equivalent Mg(1), and four equivalent Mg(3) atoms. C(1) is bonded in a 10-coordinate geometry to four equivalent Mg(1) atoms.
Mg6AlC crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Al(1), and two equivalent C(1) atoms. There is one shorter (2.83 Å) and one longer (3.07 Å) Mg(1)-Mg(1) bond length. There is one shorter (2.96 Å) and one longer (3.00 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.08 Å. Both Mg(1)-Mg(4) bond lengths are 3.04 Å. There is one shorter (2.88 Å) and one longer (3.08 Å) Mg(1)-Al(1) bond length. Both Mg(1)-C(1) bond lengths are 2.97 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Al(1) atoms to form a mixture of distorted face and corner-sharing MgMg10Al2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.03 Å. All Mg(2)-Mg(3) bond lengths are 3.02 Å. Both Mg(2)-Al(1) bond lengths are 2.95 Å. In the third Mg site, Mg(3) is bonded in a 2-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Al(1) atoms. Both Mg(3)-Al(1) bond lengths are 3.01 Å. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to two equivalent Mg(2) and four equivalent Mg(1) atoms. Al(1) is bonded in a distorted q6 geometry to two equivalent Mg(2), four equivalent Mg(1), and four equivalent Mg(3) atoms. C(1) is bonded in a 10-coordinate geometry to four equivalent Mg(1) atoms.