MgAg4 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent Ag(1) atoms to form distorted MgAg6 cuboctahedra that share corners with six equivalent Ag(2)Ag12 cuboctahedra, edges with six equivalent Mg(1)Ag6 cuboctahedra, and edges with six equivalent Ag(2)Ag12 cuboctahedra. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to three equivalent Mg(1) and three equivalent Ag(2) atoms to form distorted AgMg3Ag3 cuboctahedra that share corners with three equivalent Ag(1)Mg3Ag3 cuboctahedra, corners with nine equivalent Ag(2)Ag12 cuboctahedra, edges with nine equivalent Ag(2)Ag12 cuboctahedra, and edges with nine equivalent Ag(1)Mg3Ag3 cuboctahedra. In the second Ag site, Ag(2) is bonded to three equivalent Ag(1) and nine equivalent Ag(2) atoms to form AgAg12 cuboctahedra that share corners with three equivalent Mg(1)Ag6 cuboctahedra, corners with six equivalent Ag(2)Ag12 cuboctahedra, corners with nine equivalent Ag(1)Mg3Ag3 cuboctahedra, edges with three equivalent Mg(1)Ag6 cuboctahedra, edges with nine equivalent Ag(1)Mg3Ag3 cuboctahedra, edges with twelve equivalent Ag(2)Ag12 cuboctahedra, and faces with twelve equivalent Ag(2)Ag12 cuboctahedra.
MgAg4 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent Ag(1) atoms to form distorted MgAg6 cuboctahedra that share corners with six equivalent Ag(2)Ag12 cuboctahedra, edges with six equivalent Mg(1)Ag6 cuboctahedra, and edges with six equivalent Ag(2)Ag12 cuboctahedra. All Mg(1)-Ag(1) bond lengths are 2.89 Å. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to three equivalent Mg(1) and three equivalent Ag(2) atoms to form distorted AgMg3Ag3 cuboctahedra that share corners with three equivalent Ag(1)Mg3Ag3 cuboctahedra, corners with nine equivalent Ag(2)Ag12 cuboctahedra, edges with nine equivalent Ag(2)Ag12 cuboctahedra, and edges with nine equivalent Ag(1)Mg3Ag3 cuboctahedra. All Ag(1)-Ag(2) bond lengths are 2.93 Å. In the second Ag site, Ag(2) is bonded to three equivalent Ag(1) and nine equivalent Ag(2) atoms to form AgAg12 cuboctahedra that share corners with three equivalent Mg(1)Ag6 cuboctahedra, corners with six equivalent Ag(2)Ag12 cuboctahedra, corners with nine equivalent Ag(1)Mg3Ag3 cuboctahedra, edges with three equivalent Mg(1)Ag6 cuboctahedra, edges with nine equivalent Ag(1)Mg3Ag3 cuboctahedra, edges with twelve equivalent Ag(2)Ag12 cuboctahedra, and faces with twelve equivalent Ag(2)Ag12 cuboctahedra. There are three shorter (2.90 Å) and six longer (3.02 Å) Ag(2)-Ag(2) bond lengths.