KMg6C crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 10-coordinate geometry to two equivalent K(1), two equivalent Mg(1), two equivalent Mg(4), and four equivalent Mg(3) atoms. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in an L-shaped geometry to one K(1), two equivalent Mg(4), and two equivalent C(1) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), and four equivalent Mg(3) atoms. In the third Mg site, Mg(3) is bonded in a single-bond geometry to two equivalent K(1), one Mg(4), two equivalent Mg(2), and one C(1) atom. In the fourth Mg site, Mg(4) is bonded to two equivalent K(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and four equivalent Mg(1) atoms to form MgK2Mg10 cuboctahedra that share corners with two equivalent Mg(4)K2Mg10 cuboctahedra, corners with four equivalent C(1)Mg6 pentagonal pyramids, faces with two equivalent Mg(4)K2Mg10 cuboctahedra, and faces with two equivalent C(1)Mg6 pentagonal pyramids. C(1) is bonded to two equivalent Mg(3) and four equivalent Mg(1) atoms to form distorted CMg6 pentagonal pyramids that share corners with four equivalent Mg(4)K2Mg10 cuboctahedra, edges with two equivalent C(1)Mg6 pentagonal pyramids, and faces with two equivalent Mg(4)K2Mg10 cuboctahedra.
KMg6C crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 10-coordinate geometry to two equivalent K(1), two equivalent Mg(1), two equivalent Mg(4), and four equivalent Mg(3) atoms. Both K(1)-K(1) bond lengths are 3.26 Å. Both K(1)-Mg(1) bond lengths are 3.37 Å. Both K(1)-Mg(4) bond lengths are 3.88 Å. All K(1)-Mg(3) bond lengths are 3.60 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in an L-shaped geometry to one K(1), two equivalent Mg(4), and two equivalent C(1) atoms. Both Mg(1)-Mg(4) bond lengths are 3.19 Å. Both Mg(1)-C(1) bond lengths are 2.24 Å. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), and four equivalent Mg(3) atoms. Both Mg(2)-Mg(2) bond lengths are 3.26 Å. Both Mg(2)-Mg(4) bond lengths are 3.30 Å. All Mg(2)-Mg(3) bond lengths are 3.27 Å. In the third Mg site, Mg(3) is bonded in a single-bond geometry to two equivalent K(1), one Mg(4), two equivalent Mg(2), and one C(1) atom. The Mg(3)-Mg(4) bond length is 3.27 Å. The Mg(3)-C(1) bond length is 2.36 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent K(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and four equivalent Mg(1) atoms to form MgK2Mg10 cuboctahedra that share corners with two equivalent Mg(4)K2Mg10 cuboctahedra, corners with four equivalent C(1)Mg6 pentagonal pyramids, faces with two equivalent Mg(4)K2Mg10 cuboctahedra, and faces with two equivalent C(1)Mg6 pentagonal pyramids. Both Mg(4)-Mg(4) bond lengths are 3.26 Å. C(1) is bonded to two equivalent Mg(3) and four equivalent Mg(1) atoms to form distorted CMg6 pentagonal pyramids that share corners with four equivalent Mg(4)K2Mg10 cuboctahedra, edges with two equivalent C(1)Mg6 pentagonal pyramids, and faces with two equivalent Mg(4)K2Mg10 cuboctahedra.