Er3SmMn8 is Hexagonal Laves-derived structured and crystallizes in the monoclinic Cm space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 16-coordinate geometry to one Er(2), three equivalent Sm(1), one Mn(4), two equivalent Mn(3), two equivalent Mn(6), three equivalent Mn(1), and four equivalent Mn(5) atoms. In the second Er site, Er(2) is bonded in a 16-coordinate geometry to one Er(1), three equivalent Er(3), one Mn(4), two equivalent Mn(3), two equivalent Mn(6), three equivalent Mn(2), and four equivalent Mn(5) atoms. In the third Er site, Er(3) is bonded in a 16-coordinate geometry to three equivalent Er(2), one Sm(1), one Mn(6), two equivalent Mn(4), two equivalent Mn(5), three equivalent Mn(2), and four equivalent Mn(3) atoms. Sm(1) is bonded in a 16-coordinate geometry to one Er(3), three equivalent Er(1), one Mn(6), two equivalent Mn(4), two equivalent Mn(5), three equivalent Mn(1), and four equivalent Mn(3) atoms. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent Er(1), three equivalent Sm(1), one Mn(4), one Mn(6), two equivalent Mn(3), and two equivalent Mn(5) atoms to form MnSm3Er3Mn6 cuboctahedra that share corners with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with six equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with two equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with six equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with six equivalent Mn(5)SmEr5Mn6 cuboctahedra. In the second Mn site, Mn(2) is bonded to three equivalent Er(2), three equivalent Er(3), one Mn(4), one Mn(6), two equivalent Mn(3), and two equivalent Mn(5) atoms to form MnEr6Mn6 cuboctahedra that share corners with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with six equivalent Mn(2)Er6Mn6 cuboctahedra, faces with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with three equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with six equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with six equivalent Mn(5)SmEr5Mn6 cuboctahedra. In the third Mn site, Mn(3) is bonded to one Er(1), one Er(2), two equivalent Er(3), two equivalent Sm(1), one Mn(1), one Mn(2), two equivalent Mn(3), and two equivalent Mn(4) atoms to form MnSm2Er4Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with six equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with two equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, edges with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, faces with two equivalent Mn(5)SmEr5Mn6 cuboctahedra, faces with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra. In the fourth Mn site, Mn(4) is bonded to one Er(1), one Er(2), two equivalent Er(3), two equivalent Sm(1), one Mn(1), one Mn(2), and four equivalent Mn(3) atoms to form MnSm2Er4Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with eight equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, edges with four equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, and faces with eight equivalent Mn(3)Sm2Er4Mn6 cuboctahedra. In the fifth Mn site, Mn(5) is bonded to one Er(3), two equivalent Er(1), two equivalent Er(2), one Sm(1), one Mn(1), one Mn(2), two equivalent Mn(5), and two equivalent Mn(6) atoms to form MnSmEr5Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, corners with six equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, edges with two equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, faces with two equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, faces with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, and faces with four equivalent Mn(6)SmEr5Mn6 cuboctahedra. In the sixth Mn site, Mn(6) is bonded to one Er(3), two equivalent Er(1), two equivalent Er(2), one Sm(1), one Mn(1), one Mn(2), and four equivalent Mn(5) atoms to form MnSmEr5Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with four equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with eight equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, edges with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, edges with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with eight equivalent Mn(5)SmEr5Mn6 cuboctahedra.
Er3SmMn8 is Hexagonal Laves-derived structured and crystallizes in the monoclinic Cm space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 16-coordinate geometry to one Er(2), three equivalent Sm(1), one Mn(4), two equivalent Mn(3), two equivalent Mn(6), three equivalent Mn(1), and four equivalent Mn(5) atoms. The Er(1)-Er(2) bond length is 3.16 Å. All Er(1)-Sm(1) bond lengths are 3.13 Å. The Er(1)-Mn(4) bond length is 3.12 Å. Both Er(1)-Mn(3) bond lengths are 3.13 Å. Both Er(1)-Mn(6) bond lengths are 3.00 Å. There is one shorter (2.95 Å) and two longer (2.97 Å) Er(1)-Mn(1) bond lengths. There are two shorter (2.98 Å) and two longer (2.99 Å) Er(1)-Mn(5) bond lengths. In the second Er site, Er(2) is bonded in a 16-coordinate geometry to one Er(1), three equivalent Er(3), one Mn(4), two equivalent Mn(3), two equivalent Mn(6), three equivalent Mn(2), and four equivalent Mn(5) atoms. There is one shorter (3.11 Å) and two longer (3.13 Å) Er(2)-Er(3) bond lengths. The Er(2)-Mn(4) bond length is 3.06 Å. Both Er(2)-Mn(3) bond lengths are 3.05 Å. Both Er(2)-Mn(6) bond lengths are 2.97 Å. There is one shorter (2.96 Å) and two longer (2.97 Å) Er(2)-Mn(2) bond lengths. There are two shorter (2.95 Å) and two longer (2.97 Å) Er(2)-Mn(5) bond lengths. In the third Er site, Er(3) is bonded in a 16-coordinate geometry to three equivalent Er(2), one Sm(1), one Mn(6), two equivalent Mn(4), two equivalent Mn(5), three equivalent Mn(2), and four equivalent Mn(3) atoms. The Er(3)-Sm(1) bond length is 3.20 Å. The Er(3)-Mn(6) bond length is 3.04 Å. Both Er(3)-Mn(4) bond lengths are 2.97 Å. Both Er(3)-Mn(5) bond lengths are 3.04 Å. There is one shorter (2.95 Å) and two longer (2.97 Å) Er(3)-Mn(2) bond lengths. There are two shorter (2.96 Å) and two longer (2.98 Å) Er(3)-Mn(3) bond lengths. Sm(1) is bonded in a 16-coordinate geometry to one Er(3), three equivalent Er(1), one Mn(6), two equivalent Mn(4), two equivalent Mn(5), three equivalent Mn(1), and four equivalent Mn(3) atoms. The Sm(1)-Mn(6) bond length is 3.10 Å. Both Sm(1)-Mn(4) bond lengths are 3.01 Å. Both Sm(1)-Mn(5) bond lengths are 3.11 Å. There is one shorter (2.95 Å) and two longer (2.97 Å) Sm(1)-Mn(1) bond lengths. There are two shorter (2.99 Å) and two longer (3.01 Å) Sm(1)-Mn(3) bond lengths. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent Er(1), three equivalent Sm(1), one Mn(4), one Mn(6), two equivalent Mn(3), and two equivalent Mn(5) atoms to form MnSm3Er3Mn6 cuboctahedra that share corners with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with six equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with two equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with six equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with six equivalent Mn(5)SmEr5Mn6 cuboctahedra. The Mn(1)-Mn(4) bond length is 2.66 Å. The Mn(1)-Mn(6) bond length is 2.64 Å. Both Mn(1)-Mn(3) bond lengths are 2.65 Å. Both Mn(1)-Mn(5) bond lengths are 2.62 Å. In the second Mn site, Mn(2) is bonded to three equivalent Er(2), three equivalent Er(3), one Mn(4), one Mn(6), two equivalent Mn(3), and two equivalent Mn(5) atoms to form MnEr6Mn6 cuboctahedra that share corners with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with six equivalent Mn(2)Er6Mn6 cuboctahedra, faces with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with three equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with six equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with six equivalent Mn(5)SmEr5Mn6 cuboctahedra. The Mn(2)-Mn(4) bond length is 2.58 Å. The Mn(2)-Mn(6) bond length is 2.56 Å. Both Mn(2)-Mn(3) bond lengths are 2.60 Å. Both Mn(2)-Mn(5) bond lengths are 2.59 Å. In the third Mn site, Mn(3) is bonded to one Er(1), one Er(2), two equivalent Er(3), two equivalent Sm(1), one Mn(1), one Mn(2), two equivalent Mn(3), and two equivalent Mn(4) atoms to form MnSm2Er4Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with six equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with two equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, edges with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, faces with two equivalent Mn(5)SmEr5Mn6 cuboctahedra, faces with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra. There is one shorter (2.49 Å) and one longer (2.56 Å) Mn(3)-Mn(3) bond length. There is one shorter (2.48 Å) and one longer (2.55 Å) Mn(3)-Mn(4) bond length. In the fourth Mn site, Mn(4) is bonded to one Er(1), one Er(2), two equivalent Er(3), two equivalent Sm(1), one Mn(1), one Mn(2), and four equivalent Mn(3) atoms to form MnSm2Er4Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with eight equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, edges with four equivalent Mn(6)SmEr5Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, and faces with eight equivalent Mn(3)Sm2Er4Mn6 cuboctahedra. In the fifth Mn site, Mn(5) is bonded to one Er(3), two equivalent Er(1), two equivalent Er(2), one Sm(1), one Mn(1), one Mn(2), two equivalent Mn(5), and two equivalent Mn(6) atoms to form MnSmEr5Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, corners with six equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, edges with two equivalent Mn(5)SmEr5Mn6 cuboctahedra, edges with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, faces with two equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, faces with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(5)SmEr5Mn6 cuboctahedra, and faces with four equivalent Mn(6)SmEr5Mn6 cuboctahedra. There is one shorter (2.50 Å) and one longer (2.56 Å) Mn(5)-Mn(5) bond length. There is one shorter (2.48 Å) and one longer (2.55 Å) Mn(5)-Mn(6) bond length. In the sixth Mn site, Mn(6) is bonded to one Er(3), two equivalent Er(1), two equivalent Er(2), one Sm(1), one Mn(1), one Mn(2), and four equivalent Mn(5) atoms to form MnSmEr5Mn6 cuboctahedra that share corners with two equivalent Mn(2)Er6Mn6 cuboctahedra, corners with two equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, corners with two equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, corners with four equivalent Mn(6)SmEr5Mn6 cuboctahedra, corners with eight equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, edges with two equivalent Mn(6)SmEr5Mn6 cuboctahedra, edges with four equivalent Mn(4)Sm2Er4Mn6 cuboctahedra, faces with three equivalent Mn(2)Er6Mn6 cuboctahedra, faces with three equivalent Mn(1)Sm3Er3Mn6 cuboctahedra, faces with four equivalent Mn(3)Sm2Er4Mn6 cuboctahedra, and faces with eight equivalent Mn(5)SmEr5Mn6 cuboctahedra.