Eu16Sb11 crystallizes in the orthorhombic P2_12_12 space group. There are nine inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(3), one Sb(5), one Sb(6), and two equivalent Sb(2) atoms. In the second Eu site, Eu(2) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(3), one Sb(5), one Sb(6), and two equivalent Sb(2) atoms. In the third Eu site, Eu(3) is bonded to one Sb(1), one Sb(3), and two equivalent Sb(4) atoms to form distorted EuSb4 trigonal pyramids that share  a cornercorner with one Eu(4)Sb4 tetrahedra, corners with two equivalent Eu(8)Sb5 trigonal bipyramids, corners with two equivalent Eu(9)Sb5 trigonal bipyramids,  an edgeedge with one Eu(8)Sb5 trigonal bipyramid,  an edgeedge with one Eu(9)Sb5 trigonal bipyramid, and  an edgeedge with one Eu(3)Sb4 trigonal pyramid. In the fourth Eu site, Eu(4) is bonded to two equivalent Sb(1) and two equivalent Sb(2) atoms to form distorted EuSb4 tetrahedra that share corners with two equivalent Eu(8)Sb5 trigonal bipyramids, corners with two equivalent Eu(9)Sb5 trigonal bipyramids, and corners with two equivalent Eu(3)Sb4 trigonal pyramids. In the fifth Eu site, Eu(5) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(2), one Sb(3), one Sb(4), one Sb(6), and one Sb(7) atom. In the sixth Eu site, Eu(6) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(2), one Sb(3), one Sb(4), one Sb(5), and one Sb(7) atom. In the seventh Eu site, Eu(7) is bonded in a distorted see-saw-like geometry to two equivalent Sb(2) and two equivalent Sb(3) atoms. In the eighth Eu site, Eu(8) is bonded to one Sb(1), one Sb(3), one Sb(4), one Sb(5), and one Sb(7) atom to form distorted EuSb5 trigonal bipyramids that share  a cornercorner with one Eu(4)Sb4 tetrahedra, corners with three equivalent Eu(9)Sb5 trigonal bipyramids, corners with two equivalent Eu(3)Sb4 trigonal pyramids,  an edgeedge with one Eu(8)Sb5 trigonal bipyramid,  an edgeedge with one Eu(9)Sb5 trigonal bipyramid, and  an edgeedge with one Eu(3)Sb4 trigonal pyramid. In the ninth Eu site, Eu(9) is bonded to one Sb(1), one Sb(3), one Sb(4), one Sb(6), and one Sb(7) atom to form distorted EuSb5 trigonal bipyramids that share  a cornercorner with one Eu(4)Sb4 tetrahedra, corners with three equivalent Eu(8)Sb5 trigonal bipyramids, corners with two equivalent Eu(3)Sb4 trigonal pyramids,  an edgeedge with one Eu(8)Sb5 trigonal bipyramid,  an edgeedge with one Eu(9)Sb5 trigonal bipyramid, and  an edgeedge with one Eu(3)Sb4 trigonal pyramid. There are seven inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 8-coordinate geometry to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), one Eu(6), one Eu(8), and one Eu(9) atom. In the second Sb site, Sb(2) is bonded in a 8-coordinate geometry to one Eu(4), one Eu(5), one Eu(6), one Eu(7), two equivalent Eu(1), and two equivalent Eu(2) atoms. In the third Sb site, Sb(3) is bonded in a 8-coordinate geometry to one Eu(1), one Eu(2), one Eu(3), one Eu(5), one Eu(6), one Eu(7), one Eu(8), and one Eu(9) atom. In the fourth Sb site, Sb(4) is bonded in a 6-coordinate geometry to one Eu(5), one Eu(6), one Eu(8), one Eu(9), and two equivalent Eu(3) atoms. In the fifth Sb site, Sb(5) is bonded in a 8-coordinate geometry to two equivalent Eu(1), two equivalent Eu(2), two equivalent Eu(6), and two equivalent Eu(8) atoms. In the sixth Sb site, Sb(6) is bonded in a 8-coordinate geometry to two equivalent Eu(1), two equivalent Eu(2), two equivalent Eu(5), and two equivalent Eu(9) atoms. In the seventh Sb site, Sb(7) is bonded in a body-centered cubic geometry to two equivalent Eu(5), two equivalent Eu(6), two equivalent Eu(8), and two equivalent Eu(9) atoms.
Eu16Sb11 crystallizes in the orthorhombic P2_12_12 space group. There are nine inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(3), one Sb(5), one Sb(6), and two equivalent Sb(2) atoms. The Eu(1)-Sb(1) bond length is 3.34 Å. The Eu(1)-Sb(3) bond length is 3.34 Å. The Eu(1)-Sb(5) bond length is 3.35 Å. The Eu(1)-Sb(6) bond length is 3.39 Å. Both Eu(1)-Sb(2) bond lengths are 3.53 Å. In the second Eu site, Eu(2) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(3), one Sb(5), one Sb(6), and two equivalent Sb(2) atoms. The Eu(2)-Sb(1) bond length is 3.36 Å. The Eu(2)-Sb(3) bond length is 3.32 Å. The Eu(2)-Sb(5) bond length is 3.37 Å. The Eu(2)-Sb(6) bond length is 3.37 Å. There is one shorter (3.52 Å) and one longer (3.53 Å) Eu(2)-Sb(2) bond length. In the third Eu site, Eu(3) is bonded to one Sb(1), one Sb(3), and two equivalent Sb(4) atoms to form distorted EuSb4 trigonal pyramids that share  a cornercorner with one Eu(4)Sb4 tetrahedra, corners with two equivalent Eu(8)Sb5 trigonal bipyramids, corners with two equivalent Eu(9)Sb5 trigonal bipyramids,  an edgeedge with one Eu(8)Sb5 trigonal bipyramid,  an edgeedge with one Eu(9)Sb5 trigonal bipyramid, and  an edgeedge with one Eu(3)Sb4 trigonal pyramid. The Eu(3)-Sb(1) bond length is 3.18 Å. The Eu(3)-Sb(3) bond length is 3.22 Å. Both Eu(3)-Sb(4) bond lengths are 3.29 Å. In the fourth Eu site, Eu(4) is bonded to two equivalent Sb(1) and two equivalent Sb(2) atoms to form distorted EuSb4 tetrahedra that share corners with two equivalent Eu(8)Sb5 trigonal bipyramids, corners with two equivalent Eu(9)Sb5 trigonal bipyramids, and corners with two equivalent Eu(3)Sb4 trigonal pyramids. Both Eu(4)-Sb(1) bond lengths are 3.18 Å. Both Eu(4)-Sb(2) bond lengths are 3.33 Å. In the fifth Eu site, Eu(5) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(2), one Sb(3), one Sb(4), one Sb(6), and one Sb(7) atom. The Eu(5)-Sb(1) bond length is 3.40 Å. The Eu(5)-Sb(2) bond length is 3.72 Å. The Eu(5)-Sb(3) bond length is 3.57 Å. The Eu(5)-Sb(4) bond length is 3.20 Å. The Eu(5)-Sb(6) bond length is 3.27 Å. The Eu(5)-Sb(7) bond length is 3.75 Å. In the sixth Eu site, Eu(6) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(2), one Sb(3), one Sb(4), one Sb(5), and one Sb(7) atom. The Eu(6)-Sb(1) bond length is 3.42 Å. The Eu(6)-Sb(2) bond length is 3.73 Å. The Eu(6)-Sb(3) bond length is 3.61 Å. The Eu(6)-Sb(4) bond length is 3.21 Å. The Eu(6)-Sb(5) bond length is 3.28 Å. The Eu(6)-Sb(7) bond length is 3.69 Å. In the seventh Eu site, Eu(7) is bonded in a distorted see-saw-like geometry to two equivalent Sb(2) and two equivalent Sb(3) atoms. Both Eu(7)-Sb(2) bond lengths are 3.33 Å. Both Eu(7)-Sb(3) bond lengths are 3.26 Å. In the eighth Eu site, Eu(8) is bonded to one Sb(1), one Sb(3), one Sb(4), one Sb(5), and one Sb(7) atom to form distorted EuSb5 trigonal bipyramids that share  a cornercorner with one Eu(4)Sb4 tetrahedra, corners with three equivalent Eu(9)Sb5 trigonal bipyramids, corners with two equivalent Eu(3)Sb4 trigonal pyramids,  an edgeedge with one Eu(8)Sb5 trigonal bipyramid,  an edgeedge with one Eu(9)Sb5 trigonal bipyramid, and  an edgeedge with one Eu(3)Sb4 trigonal pyramid. The Eu(8)-Sb(1) bond length is 3.55 Å. The Eu(8)-Sb(3) bond length is 3.33 Å. The Eu(8)-Sb(4) bond length is 3.28 Å. The Eu(8)-Sb(5) bond length is 3.36 Å. The Eu(8)-Sb(7) bond length is 3.51 Å. In the ninth Eu site, Eu(9) is bonded to one Sb(1), one Sb(3), one Sb(4), one Sb(6), and one Sb(7) atom to form distorted EuSb5 trigonal bipyramids that share  a cornercorner with one Eu(4)Sb4 tetrahedra, corners with three equivalent Eu(8)Sb5 trigonal bipyramids, corners with two equivalent Eu(3)Sb4 trigonal pyramids,  an edgeedge with one Eu(8)Sb5 trigonal bipyramid,  an edgeedge with one Eu(9)Sb5 trigonal bipyramid, and  an edgeedge with one Eu(3)Sb4 trigonal pyramid. The Eu(9)-Sb(1) bond length is 3.57 Å. The Eu(9)-Sb(3) bond length is 3.35 Å. The Eu(9)-Sb(4) bond length is 3.27 Å. The Eu(9)-Sb(6) bond length is 3.31 Å. The Eu(9)-Sb(7) bond length is 3.46 Å. There are seven inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 8-coordinate geometry to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), one Eu(6), one Eu(8), and one Eu(9) atom. In the second Sb site, Sb(2) is bonded in a 8-coordinate geometry to one Eu(4), one Eu(5), one Eu(6), one Eu(7), two equivalent Eu(1), and two equivalent Eu(2) atoms. In the third Sb site, Sb(3) is bonded in a 8-coordinate geometry to one Eu(1), one Eu(2), one Eu(3), one Eu(5), one Eu(6), one Eu(7), one Eu(8), and one Eu(9) atom. In the fourth Sb site, Sb(4) is bonded in a 6-coordinate geometry to one Eu(5), one Eu(6), one Eu(8), one Eu(9), and two equivalent Eu(3) atoms. In the fifth Sb site, Sb(5) is bonded in a 8-coordinate geometry to two equivalent Eu(1), two equivalent Eu(2), two equivalent Eu(6), and two equivalent Eu(8) atoms. In the sixth Sb site, Sb(6) is bonded in a 8-coordinate geometry to two equivalent Eu(1), two equivalent Eu(2), two equivalent Eu(5), and two equivalent Eu(9) atoms. In the seventh Sb site, Sb(7) is bonded in a body-centered cubic geometry to two equivalent Eu(5), two equivalent Eu(6), two equivalent Eu(8), and two equivalent Eu(9) atoms.