Mg3GdNi8 is Hexagonal Laves-derived structured and crystallizes in the trigonal R3m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 16-coordinate geometry to one Mg(3), three equivalent Mg(2), three equivalent Ni(1), three equivalent Ni(3), and six equivalent Ni(2) atoms. In the second Mg site, Mg(2) is bonded in a 16-coordinate geometry to three equivalent Mg(1), one Gd(1), three equivalent Ni(2), three equivalent Ni(3), and six equivalent Ni(1) atoms. In the third Mg site, Mg(3) is bonded in a 16-coordinate geometry to one Mg(1), three equivalent Gd(1), three equivalent Ni(1), three equivalent Ni(4), and six equivalent Ni(2) atoms. Gd(1) is bonded in a 16-coordinate geometry to one Mg(2), three equivalent Mg(3), three equivalent Ni(2), three equivalent Ni(4), and six equivalent Ni(1) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one Mg(1), one Mg(3), two equivalent Mg(2), two equivalent Gd(1), one Ni(3), one Ni(4), and four equivalent Ni(1) atoms to form NiGd2Mg4Ni6 cuboctahedra that share corners with two equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, corners with two equivalent Ni(3)Mg6Ni6 cuboctahedra, corners with four equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, corners with ten equivalent Ni(2)GdMg5Ni6 cuboctahedra, edges with two equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, edges with four equivalent Ni(2)GdMg5Ni6 cuboctahedra, faces with three equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, faces with three equivalent Ni(3)Mg6Ni6 cuboctahedra, faces with four equivalent Ni(2)GdMg5Ni6 cuboctahedra, and faces with eight equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra. In the second Ni site, Ni(2) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), one Gd(1), one Ni(3), one Ni(4), and four equivalent Ni(2) atoms to form NiGdMg5Ni6 cuboctahedra that share corners with two equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, corners with two equivalent Ni(3)Mg6Ni6 cuboctahedra, corners with four equivalent Ni(2)GdMg5Ni6 cuboctahedra, corners with ten equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, edges with two equivalent Ni(2)GdMg5Ni6 cuboctahedra, edges with four equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, faces with three equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, faces with three equivalent Ni(3)Mg6Ni6 cuboctahedra, faces with four equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, and faces with eight equivalent Ni(2)GdMg5Ni6 cuboctahedra. In the third Ni site, Ni(3) is bonded to three equivalent Mg(1), three equivalent Mg(2), three equivalent Ni(1), and three equivalent Ni(2) atoms to form NiMg6Ni6 cuboctahedra that share corners with six equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, corners with six equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, corners with six equivalent Ni(2)GdMg5Ni6 cuboctahedra, edges with six equivalent Ni(3)Mg6Ni6 cuboctahedra, faces with nine equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, and faces with nine equivalent Ni(2)GdMg5Ni6 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to three equivalent Mg(3), three equivalent Gd(1), three equivalent Ni(1), and three equivalent Ni(2) atoms to form NiGd3Mg3Ni6 cuboctahedra that share corners with six equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, corners with six equivalent Ni(2)GdMg5Ni6 cuboctahedra, corners with six equivalent Ni(3)Mg6Ni6 cuboctahedra, edges with six equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, faces with nine equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, and faces with nine equivalent Ni(2)GdMg5Ni6 cuboctahedra.
Mg3GdNi8 is Hexagonal Laves-derived structured and crystallizes in the trigonal R3m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 16-coordinate geometry to one Mg(3), three equivalent Mg(2), three equivalent Ni(1), three equivalent Ni(3), and six equivalent Ni(2) atoms. The Mg(1)-Mg(3) bond length is 2.89 Å. All Mg(1)-Mg(2) bond lengths are 2.96 Å. All Mg(1)-Ni(1) bond lengths are 2.81 Å. All Mg(1)-Ni(3) bond lengths are 2.86 Å. All Mg(1)-Ni(2) bond lengths are 2.85 Å. In the second Mg site, Mg(2) is bonded in a 16-coordinate geometry to three equivalent Mg(1), one Gd(1), three equivalent Ni(2), three equivalent Ni(3), and six equivalent Ni(1) atoms. The Mg(2)-Gd(1) bond length is 3.06 Å. All Mg(2)-Ni(2) bond lengths are 2.75 Å. All Mg(2)-Ni(3) bond lengths are 2.85 Å. All Mg(2)-Ni(1) bond lengths are 2.88 Å. In the third Mg site, Mg(3) is bonded in a 16-coordinate geometry to one Mg(1), three equivalent Gd(1), three equivalent Ni(1), three equivalent Ni(4), and six equivalent Ni(2) atoms. All Mg(3)-Gd(1) bond lengths are 3.03 Å. All Mg(3)-Ni(1) bond lengths are 2.99 Å. All Mg(3)-Ni(4) bond lengths are 2.88 Å. All Mg(3)-Ni(2) bond lengths are 2.83 Å. Gd(1) is bonded in a 16-coordinate geometry to one Mg(2), three equivalent Mg(3), three equivalent Ni(2), three equivalent Ni(4), and six equivalent Ni(1) atoms. All Gd(1)-Ni(2) bond lengths are 2.90 Å. All Gd(1)-Ni(4) bond lengths are 2.87 Å. All Gd(1)-Ni(1) bond lengths are 2.88 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one Mg(1), one Mg(3), two equivalent Mg(2), two equivalent Gd(1), one Ni(3), one Ni(4), and four equivalent Ni(1) atoms to form NiGd2Mg4Ni6 cuboctahedra that share corners with two equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, corners with two equivalent Ni(3)Mg6Ni6 cuboctahedra, corners with four equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, corners with ten equivalent Ni(2)GdMg5Ni6 cuboctahedra, edges with two equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, edges with four equivalent Ni(2)GdMg5Ni6 cuboctahedra, faces with three equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, faces with three equivalent Ni(3)Mg6Ni6 cuboctahedra, faces with four equivalent Ni(2)GdMg5Ni6 cuboctahedra, and faces with eight equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra. The Ni(1)-Ni(3) bond length is 2.41 Å. The Ni(1)-Ni(4) bond length is 2.48 Å. There are two shorter (2.44 Å) and two longer (2.45 Å) Ni(1)-Ni(1) bond lengths. In the second Ni site, Ni(2) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), one Gd(1), one Ni(3), one Ni(4), and four equivalent Ni(2) atoms to form NiGdMg5Ni6 cuboctahedra that share corners with two equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, corners with two equivalent Ni(3)Mg6Ni6 cuboctahedra, corners with four equivalent Ni(2)GdMg5Ni6 cuboctahedra, corners with ten equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, edges with two equivalent Ni(2)GdMg5Ni6 cuboctahedra, edges with four equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, faces with three equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, faces with three equivalent Ni(3)Mg6Ni6 cuboctahedra, faces with four equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, and faces with eight equivalent Ni(2)GdMg5Ni6 cuboctahedra. The Ni(2)-Ni(3) bond length is 2.42 Å. The Ni(2)-Ni(4) bond length is 2.45 Å. There are two shorter (2.42 Å) and two longer (2.47 Å) Ni(2)-Ni(2) bond lengths. In the third Ni site, Ni(3) is bonded to three equivalent Mg(1), three equivalent Mg(2), three equivalent Ni(1), and three equivalent Ni(2) atoms to form NiMg6Ni6 cuboctahedra that share corners with six equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, corners with six equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, corners with six equivalent Ni(2)GdMg5Ni6 cuboctahedra, edges with six equivalent Ni(3)Mg6Ni6 cuboctahedra, faces with nine equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, and faces with nine equivalent Ni(2)GdMg5Ni6 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to three equivalent Mg(3), three equivalent Gd(1), three equivalent Ni(1), and three equivalent Ni(2) atoms to form NiGd3Mg3Ni6 cuboctahedra that share corners with six equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, corners with six equivalent Ni(2)GdMg5Ni6 cuboctahedra, corners with six equivalent Ni(3)Mg6Ni6 cuboctahedra, edges with six equivalent Ni(4)Gd3Mg3Ni6 cuboctahedra, faces with nine equivalent Ni(1)Gd2Mg4Ni6 cuboctahedra, and faces with nine equivalent Ni(2)GdMg5Ni6 cuboctahedra.