Er3CoAl3Ge2 crystallizes in the hexagonal P-62m space group. Er(1) is bonded in a 5-coordinate geometry to one Co(1), six equivalent Al(1), and four equivalent Ge(1) atoms. Co(1) is bonded in a distorted q6 geometry to three equivalent Er(1) and six equivalent Al(1) atoms. Al(1) is bonded to six equivalent Er(1), two equivalent Co(1), two equivalent Al(1), and two equivalent Ge(1) atoms to form a mixture of distorted corner, edge, and face-sharing AlEr6Al2Co2Ge2 tetrahedra. Ge(1) is bonded in a 9-coordinate geometry to six equivalent Er(1) and three equivalent Al(1) atoms.
Er3CoAl3Ge2 crystallizes in the hexagonal P-62m space group. Er(1) is bonded in a 5-coordinate geometry to one Co(1), six equivalent Al(1), and four equivalent Ge(1) atoms. The Er(1)-Co(1) bond length is 2.78 Å. There are four shorter (3.18 Å) and two longer (3.29 Å) Er(1)-Al(1) bond lengths. All Er(1)-Ge(1) bond lengths are 2.95 Å. Co(1) is bonded in a distorted q6 geometry to three equivalent Er(1) and six equivalent Al(1) atoms. All Co(1)-Al(1) bond lengths are 2.60 Å. Al(1) is bonded to six equivalent Er(1), two equivalent Co(1), two equivalent Al(1), and two equivalent Ge(1) atoms to form a mixture of distorted corner, edge, and face-sharing AlEr6Al2Co2Ge2 tetrahedra. Both Al(1)-Al(1) bond lengths are 2.71 Å. Both Al(1)-Ge(1) bond lengths are 2.74 Å. Ge(1) is bonded in a 9-coordinate geometry to six equivalent Er(1) and three equivalent Al(1) atoms.