Co4Ge crystallizes in the trigonal R-3m space group. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to three equivalent Co(2), six equivalent Co(1), and three equivalent Ge(1) atoms to form CoCo9Ge3 cuboctahedra that share corners with three equivalent Co(2)Co12 cuboctahedra, corners with nine equivalent Co(1)Co9Ge3 cuboctahedra, edges with six equivalent Ge(1)Co6Ge6 cuboctahedra, edges with nine equivalent Co(2)Co12 cuboctahedra, edges with nine equivalent Co(1)Co9Ge3 cuboctahedra, faces with six equivalent Co(2)Co12 cuboctahedra, faces with six equivalent Co(1)Co9Ge3 cuboctahedra, and faces with six equivalent Ge(1)Co6Ge6 cuboctahedra. In the second Co site, Co(2) is bonded to three equivalent Co(1) and nine equivalent Co(2) atoms to form CoCo12 cuboctahedra that share corners with three equivalent Co(1)Co9Ge3 cuboctahedra, corners with three equivalent Ge(1)Co6Ge6 cuboctahedra, corners with six equivalent Co(2)Co12 cuboctahedra, edges with three equivalent Ge(1)Co6Ge6 cuboctahedra, edges with nine equivalent Co(1)Co9Ge3 cuboctahedra, edges with twelve equivalent Co(2)Co12 cuboctahedra, faces with six equivalent Co(1)Co9Ge3 cuboctahedra, and faces with twelve equivalent Co(2)Co12 cuboctahedra. In the third Co site, Co(2) is bonded to three equivalent Co(1) and nine Co(2,2) atoms to form CoCo12 cuboctahedra that share corners with three equivalent Co(1)Co9Ge3 cuboctahedra; corners with three equivalent Ge(1)Co6Ge6 cuboctahedra; corners with six equivalent Co(2)Co12 cuboctahedra; edges with three equivalent Ge(1)Co6Ge6 cuboctahedra; edges with nine equivalent Co(1)Co9Ge3 cuboctahedra; edges with twelve Co(2,2)Co12 cuboctahedra; faces with six equivalent Co(1)Co9Ge3 cuboctahedra; and faces with twelve Co(2,2)Co12 cuboctahedra. In the fourth Co site, Co(2) is bonded to three equivalent Co(1) and nine Co(2,2) atoms to form CoCo12 cuboctahedra that share corners with three equivalent Co(1)Co9Ge3 cuboctahedra; corners with three equivalent Ge(1)Co6Ge6 cuboctahedra; corners with six equivalent Co(2)Co12 cuboctahedra; edges with three equivalent Ge(1)Co6Ge6 cuboctahedra; edges with nine equivalent Co(1)Co9Ge3 cuboctahedra; edges with twelve Co(2,2)Co12 cuboctahedra; faces with six equivalent Co(1)Co9Ge3 cuboctahedra; and faces with twelve Co(2,2)Co12 cuboctahedra. Ge(1) is bonded to six equivalent Co(1) and six equivalent Ge(1) atoms to form GeCo6Ge6 cuboctahedra that share corners with six Co(2,2)Co12 cuboctahedra; corners with six equivalent Ge(1)Co6Ge6 cuboctahedra; edges with six Co(2,2)Co12 cuboctahedra; edges with six equivalent Ge(1)Co6Ge6 cuboctahedra; edges with twelve equivalent Co(1)Co9Ge3 cuboctahedra; faces with six equivalent Ge(1)Co6Ge6 cuboctahedra; and faces with twelve equivalent Co(1)Co9Ge3 cuboctahedra.
Co4Ge crystallizes in the trigonal R-3m space group. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to three equivalent Co(2), six equivalent Co(1), and three equivalent Ge(1) atoms to form CoCo9Ge3 cuboctahedra that share corners with three equivalent Co(2)Co12 cuboctahedra, corners with nine equivalent Co(1)Co9Ge3 cuboctahedra, edges with six equivalent Ge(1)Co6Ge6 cuboctahedra, edges with nine equivalent Co(2)Co12 cuboctahedra, edges with nine equivalent Co(1)Co9Ge3 cuboctahedra, faces with six equivalent Co(2)Co12 cuboctahedra, faces with six equivalent Co(1)Co9Ge3 cuboctahedra, and faces with six equivalent Ge(1)Co6Ge6 cuboctahedra. All Co(1)-Co(2) bond lengths are 2.45 Å. All Co(1)-Co(1) bond lengths are 2.62 Å. All Co(1)-Ge(1) bond lengths are 2.51 Å. In the second Co site, Co(2) is bonded to three equivalent Co(1) and nine equivalent Co(2) atoms to form CoCo12 cuboctahedra that share corners with three equivalent Co(1)Co9Ge3 cuboctahedra, corners with three equivalent Ge(1)Co6Ge6 cuboctahedra, corners with six equivalent Co(2)Co12 cuboctahedra, edges with three equivalent Ge(1)Co6Ge6 cuboctahedra, edges with nine equivalent Co(1)Co9Ge3 cuboctahedra, edges with twelve equivalent Co(2)Co12 cuboctahedra, faces with six equivalent Co(1)Co9Ge3 cuboctahedra, and faces with twelve equivalent Co(2)Co12 cuboctahedra. There are three shorter (2.50 Å) and six longer (2.62 Å) Co(2)-Co(2) bond lengths. In the third Co site, Co(2) is bonded to three equivalent Co(1) and nine Co(2,2) atoms to form CoCo12 cuboctahedra that share corners with three equivalent Co(1)Co9Ge3 cuboctahedra; corners with three equivalent Ge(1)Co6Ge6 cuboctahedra; corners with six equivalent Co(2)Co12 cuboctahedra; edges with three equivalent Ge(1)Co6Ge6 cuboctahedra; edges with nine equivalent Co(1)Co9Ge3 cuboctahedra; edges with twelve Co(2,2)Co12 cuboctahedra; faces with six equivalent Co(1)Co9Ge3 cuboctahedra; and faces with twelve Co(2,2)Co12 cuboctahedra. All Co(2)-Co(1) bond lengths are 2.45 Å. There are three shorter (2.50 Å) and six longer (2.62 Å) Co(2)-Co(2,2) bond lengths. In the fourth Co site, Co(2) is bonded to three equivalent Co(1) and nine Co(2,2) atoms to form CoCo12 cuboctahedra that share corners with three equivalent Co(1)Co9Ge3 cuboctahedra; corners with three equivalent Ge(1)Co6Ge6 cuboctahedra; corners with six equivalent Co(2)Co12 cuboctahedra; edges with three equivalent Ge(1)Co6Ge6 cuboctahedra; edges with nine equivalent Co(1)Co9Ge3 cuboctahedra; edges with twelve Co(2,2)Co12 cuboctahedra; faces with six equivalent Co(1)Co9Ge3 cuboctahedra; and faces with twelve Co(2,2)Co12 cuboctahedra. All Co(2)-Co(1) bond lengths are 2.45 Å. All Co(2)-Co(2) bond lengths are 2.62 Å. Ge(1) is bonded to six equivalent Co(1) and six equivalent Ge(1) atoms to form GeCo6Ge6 cuboctahedra that share corners with six Co(2,2)Co12 cuboctahedra; corners with six equivalent Ge(1)Co6Ge6 cuboctahedra; edges with six Co(2,2)Co12 cuboctahedra; edges with six equivalent Ge(1)Co6Ge6 cuboctahedra; edges with twelve equivalent Co(1)Co9Ge3 cuboctahedra; faces with six equivalent Ge(1)Co6Ge6 cuboctahedra; and faces with twelve equivalent Co(1)Co9Ge3 cuboctahedra. All Ge(1)-Ge(1) bond lengths are 2.62 Å.