Sr5Al2Sb6 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one Al(2), one Sb(1), one Sb(2), one Sb(4), two equivalent Sb(3), and two equivalent Sb(5) atoms. In the second Sr site, Sr(2) is bonded to one Sb(4), two equivalent Sb(1), two equivalent Sb(2), and two equivalent Sb(3) atoms to form distorted SrSb7 pentagonal bipyramids that share corners with three equivalent Al(1)Sb4 tetrahedra, corners with three equivalent Al(2)Sr2Sb4 tetrahedra, edges with two equivalent Sr(2)Sb7 pentagonal bipyramids, and  an edgeedge with one Al(1)Sb4 tetrahedra. In the third Sr site, Sr(3) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(3), one Sb(4), one Sb(5), and two equivalent Sb(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one Sb(1), one Sb(4), and two equivalent Sb(2) atoms to form AlSb4 tetrahedra that share corners with three equivalent Sr(2)Sb7 pentagonal bipyramids,  a cornercorner with one Al(2)Sr2Sb4 tetrahedra,  an edgeedge with one Sr(2)Sb7 pentagonal bipyramid, and  an edgeedge with one Al(2)Sr2Sb4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent Sr(1), one Sb(4), one Sb(5), and two equivalent Sb(2) atoms to form distorted AlSr2Sb4 tetrahedra that share corners with three equivalent Sr(2)Sb7 pentagonal bipyramids,  a cornercorner with one Al(1)Sb4 tetrahedra, and  an edgeedge with one Al(1)Sb4 tetrahedra. There are five inequivalent Sb sites. In the first Sb site, Sb(4) is bonded in a 7-coordinate geometry to one Sr(2), two equivalent Sr(1), two equivalent Sr(3), one Al(1), and one Al(2) atom. In the second Sb site, Sb(5) is bonded in a 8-coordinate geometry to two equivalent Sr(3), four equivalent Sr(1), one Al(2), and one Sb(3) atom. In the third Sb site, Sb(1) is bonded in a 7-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Sr(3), and one Al(1) atom. In the fourth Sb site, Sb(2) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), two equivalent Sr(3), one Al(1), and one Al(2) atom. In the fifth Sb site, Sb(3) is bonded in a 9-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), four equivalent Sr(1), and one Sb(5) atom.
Sr5Al2Sb6 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one Al(2), one Sb(1), one Sb(2), one Sb(4), two equivalent Sb(3), and two equivalent Sb(5) atoms. The Sr(1)-Al(2) bond length is 3.62 Å. The Sr(1)-Sb(1) bond length is 3.49 Å. The Sr(1)-Sb(2) bond length is 3.40 Å. The Sr(1)-Sb(4) bond length is 3.62 Å. There is one shorter (3.74 Å) and one longer (3.84 Å) Sr(1)-Sb(3) bond length. There is one shorter (3.57 Å) and one longer (3.59 Å) Sr(1)-Sb(5) bond length. In the second Sr site, Sr(2) is bonded to one Sb(4), two equivalent Sb(1), two equivalent Sb(2), and two equivalent Sb(3) atoms to form distorted SrSb7 pentagonal bipyramids that share corners with three equivalent Al(1)Sb4 tetrahedra, corners with three equivalent Al(2)Sr2Sb4 tetrahedra, edges with two equivalent Sr(2)Sb7 pentagonal bipyramids, and  an edgeedge with one Al(1)Sb4 tetrahedra. The Sr(2)-Sb(4) bond length is 3.38 Å. There is one shorter (3.52 Å) and one longer (3.85 Å) Sr(2)-Sb(1) bond length. Both Sr(2)-Sb(2) bond lengths are 3.21 Å. There is one shorter (3.64 Å) and one longer (3.67 Å) Sr(2)-Sb(3) bond length. In the third Sr site, Sr(3) is bonded in a 6-coordinate geometry to one Sb(1), one Sb(3), one Sb(4), one Sb(5), and two equivalent Sb(2) atoms. The Sr(3)-Sb(1) bond length is 3.37 Å. The Sr(3)-Sb(3) bond length is 3.47 Å. The Sr(3)-Sb(4) bond length is 3.41 Å. The Sr(3)-Sb(5) bond length is 3.45 Å. There is one shorter (3.24 Å) and one longer (3.28 Å) Sr(3)-Sb(2) bond length. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one Sb(1), one Sb(4), and two equivalent Sb(2) atoms to form AlSb4 tetrahedra that share corners with three equivalent Sr(2)Sb7 pentagonal bipyramids,  a cornercorner with one Al(2)Sr2Sb4 tetrahedra,  an edgeedge with one Sr(2)Sb7 pentagonal bipyramid, and  an edgeedge with one Al(2)Sr2Sb4 tetrahedra. The Al(1)-Sb(1) bond length is 2.67 Å. The Al(1)-Sb(4) bond length is 2.78 Å. Both Al(1)-Sb(2) bond lengths are 2.71 Å. In the second Al site, Al(2) is bonded to two equivalent Sr(1), one Sb(4), one Sb(5), and two equivalent Sb(2) atoms to form distorted AlSr2Sb4 tetrahedra that share corners with three equivalent Sr(2)Sb7 pentagonal bipyramids,  a cornercorner with one Al(1)Sb4 tetrahedra, and  an edgeedge with one Al(1)Sb4 tetrahedra. The Al(2)-Sb(4) bond length is 2.70 Å. The Al(2)-Sb(5) bond length is 2.76 Å. Both Al(2)-Sb(2) bond lengths are 2.67 Å. There are five inequivalent Sb sites. In the first Sb site, Sb(4) is bonded in a 7-coordinate geometry to one Sr(2), two equivalent Sr(1), two equivalent Sr(3), one Al(1), and one Al(2) atom. In the second Sb site, Sb(5) is bonded in a 8-coordinate geometry to two equivalent Sr(3), four equivalent Sr(1), one Al(2), and one Sb(3) atom. The Sb(5)-Sb(3) bond length is 2.91 Å. In the third Sb site, Sb(1) is bonded in a 7-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Sr(3), and one Al(1) atom. In the fourth Sb site, Sb(2) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), two equivalent Sr(3), one Al(1), and one Al(2) atom. In the fifth Sb site, Sb(3) is bonded in a 9-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), four equivalent Sr(1), and one Sb(5) atom.