Er6Al2Ge7 crystallizes in the monoclinic C2/m space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 8-coordinate geometry to two equivalent Ge(2), three equivalent Ge(4), and four equivalent Ge(1) atoms. In the second Er site, Er(2) is bonded in a 8-coordinate geometry to two equivalent Al(1), one Ge(3), one Ge(4), two equivalent Ge(1), and three equivalent Ge(2) atoms. In the third Er site, Er(3) is bonded in a 8-coordinate geometry to two equivalent Al(1), one Ge(2), and five equivalent Ge(3) atoms. Al(1) is bonded in a 4-coordinate geometry to two equivalent Er(2), two equivalent Er(3), two equivalent Ge(2), and two equivalent Ge(3) atoms. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 9-coordinate geometry to two equivalent Er(2), four equivalent Er(1), one Ge(2), and two equivalent Ge(4) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to one Er(3), two equivalent Er(1), three equivalent Er(2), two equivalent Al(1), and one Ge(1) atom. In the third Ge site, Ge(3) is bonded in a 9-coordinate geometry to one Er(2), five equivalent Er(3), two equivalent Al(1), and one Ge(3) atom. In the fourth Ge site, Ge(4) is bonded to two equivalent Er(2), six equivalent Er(1), and four equivalent Ge(1) atoms to form a mixture of distorted edge and face-sharing GeEr8Ge4 cuboctahedra.
Er6Al2Ge7 crystallizes in the monoclinic C2/m space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 8-coordinate geometry to two equivalent Ge(2), three equivalent Ge(4), and four equivalent Ge(1) atoms. Both Er(1)-Ge(2) bond lengths are 3.08 Å. There are two shorter (3.15 Å) and one longer (3.58 Å) Er(1)-Ge(4) bond length. There is one shorter (3.01 Å) and three longer (3.02 Å) Er(1)-Ge(1) bond lengths. In the second Er site, Er(2) is bonded in a 8-coordinate geometry to two equivalent Al(1), one Ge(3), one Ge(4), two equivalent Ge(1), and three equivalent Ge(2) atoms. Both Er(2)-Al(1) bond lengths are 3.19 Å. The Er(2)-Ge(3) bond length is 3.02 Å. The Er(2)-Ge(4) bond length is 3.60 Å. Both Er(2)-Ge(1) bond lengths are 3.02 Å. There is one shorter (2.99 Å) and two longer (3.03 Å) Er(2)-Ge(2) bond lengths. In the third Er site, Er(3) is bonded in a 8-coordinate geometry to two equivalent Al(1), one Ge(2), and five equivalent Ge(3) atoms. Both Er(3)-Al(1) bond lengths are 3.19 Å. The Er(3)-Ge(2) bond length is 3.00 Å. There are a spread of Er(3)-Ge(3) bond distances ranging from 3.01-3.04 Å. Al(1) is bonded in a 4-coordinate geometry to two equivalent Er(2), two equivalent Er(3), two equivalent Ge(2), and two equivalent Ge(3) atoms. Both Al(1)-Ge(2) bond lengths are 2.68 Å. Both Al(1)-Ge(3) bond lengths are 2.70 Å. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 9-coordinate geometry to two equivalent Er(2), four equivalent Er(1), one Ge(2), and two equivalent Ge(4) atoms. The Ge(1)-Ge(2) bond length is 2.57 Å. Both Ge(1)-Ge(4) bond lengths are 2.75 Å. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to one Er(3), two equivalent Er(1), three equivalent Er(2), two equivalent Al(1), and one Ge(1) atom. In the third Ge site, Ge(3) is bonded in a 9-coordinate geometry to one Er(2), five equivalent Er(3), two equivalent Al(1), and one Ge(3) atom. The Ge(3)-Ge(3) bond length is 2.61 Å. In the fourth Ge site, Ge(4) is bonded to two equivalent Er(2), six equivalent Er(1), and four equivalent Ge(1) atoms to form a mixture of distorted edge and face-sharing GeEr8Ge4 cuboctahedra.