Sr13Al6Si8O crystallizes in the monoclinic C2/m space group. There are seven inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to two equivalent Al(2), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. In the second Sr site, Sr(2) is bonded in a single-bond geometry to two equivalent Al(1), two equivalent Al(3), two equivalent Si(3), two equivalent Si(4), and one O(1) atom. In the third Sr site, Sr(3) is bonded to two equivalent Al(1), two equivalent Al(3), four equivalent Al(2), two equivalent Si(1), and two equivalent Si(2) atoms to form a mixture of face and edge-sharing SrAl8Si4 cuboctahedra. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to two equivalent Al(3), two equivalent Si(2), and three equivalent Si(4) atoms. In the fifth Sr site, Sr(5) is bonded in a 7-coordinate geometry to two equivalent Al(1), two equivalent Si(3), and three equivalent Si(1) atoms. In the sixth Sr site, Sr(6) is bonded in a distorted single-bond geometry to one Si(2), two equivalent Si(3), two equivalent Si(4), and one O(1) atom. In the seventh Sr site, Sr(7) is bonded in a linear geometry to two equivalent Si(3), two equivalent Si(4), and two equivalent O(1) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), two equivalent Sr(5), one Al(3), one Si(1), and one Si(3) atom. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to two equivalent Sr(1), four equivalent Sr(3), one Al(2), one Si(1), and one Si(2) atom. In the third Al site, Al(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Sr(2), two equivalent Sr(3), two equivalent Sr(4), one Al(1), one Si(2), and one Si(4) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), three equivalent Sr(5), one Al(1), and one Al(2) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Sr(6), two equivalent Sr(1), two equivalent Sr(3), two equivalent Sr(4), one Al(2), and one Al(3) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Sr(1), one Sr(7), two equivalent Sr(2), two equivalent Sr(5), two equivalent Sr(6), and one Al(1) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Sr(7), two equivalent Sr(2), two equivalent Sr(6), three equivalent Sr(4), and one Al(3) atom. O(1) is bonded to two equivalent Sr(2), two equivalent Sr(6), and two equivalent Sr(7) atoms to form corner-sharing OSr6 octahedra. The corner-sharing octahedra are not tilted.
Sr13Al6Si8O crystallizes in the monoclinic C2/m space group. There are seven inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to two equivalent Al(2), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. Both Sr(1)-Al(2) bond lengths are 3.36 Å. The Sr(1)-Si(3) bond length is 3.29 Å. Both Sr(1)-Si(1) bond lengths are 3.39 Å. Both Sr(1)-Si(2) bond lengths are 3.32 Å. In the second Sr site, Sr(2) is bonded in a single-bond geometry to two equivalent Al(1), two equivalent Al(3), two equivalent Si(3), two equivalent Si(4), and one O(1) atom. Both Sr(2)-Al(1) bond lengths are 3.42 Å. Both Sr(2)-Al(3) bond lengths are 3.44 Å. Both Sr(2)-Si(3) bond lengths are 3.47 Å. Both Sr(2)-Si(4) bond lengths are 3.44 Å. The Sr(2)-O(1) bond length is 2.50 Å. In the third Sr site, Sr(3) is bonded to two equivalent Al(1), two equivalent Al(3), four equivalent Al(2), two equivalent Si(1), and two equivalent Si(2) atoms to form a mixture of face and edge-sharing SrAl8Si4 cuboctahedra. Both Sr(3)-Al(1) bond lengths are 3.46 Å. Both Sr(3)-Al(3) bond lengths are 3.48 Å. There are two shorter (3.44 Å) and two longer (3.47 Å) Sr(3)-Al(2) bond lengths. Both Sr(3)-Si(1) bond lengths are 3.57 Å. Both Sr(3)-Si(2) bond lengths are 3.61 Å. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to two equivalent Al(3), two equivalent Si(2), and three equivalent Si(4) atoms. Both Sr(4)-Al(3) bond lengths are 3.31 Å. Both Sr(4)-Si(2) bond lengths are 3.40 Å. There is one shorter (3.25 Å) and two longer (3.41 Å) Sr(4)-Si(4) bond lengths. In the fifth Sr site, Sr(5) is bonded in a 7-coordinate geometry to two equivalent Al(1), two equivalent Si(3), and three equivalent Si(1) atoms. Both Sr(5)-Al(1) bond lengths are 3.29 Å. Both Sr(5)-Si(3) bond lengths are 3.33 Å. There is one shorter (3.29 Å) and two longer (3.40 Å) Sr(5)-Si(1) bond lengths. In the sixth Sr site, Sr(6) is bonded in a distorted single-bond geometry to one Si(2), two equivalent Si(3), two equivalent Si(4), and one O(1) atom. The Sr(6)-Si(2) bond length is 3.75 Å. Both Sr(6)-Si(3) bond lengths are 3.41 Å. Both Sr(6)-Si(4) bond lengths are 3.41 Å. The Sr(6)-O(1) bond length is 2.89 Å. In the seventh Sr site, Sr(7) is bonded in a linear geometry to two equivalent Si(3), two equivalent Si(4), and two equivalent O(1) atoms. Both Sr(7)-Si(3) bond lengths are 3.41 Å. Both Sr(7)-Si(4) bond lengths are 3.42 Å. Both Sr(7)-O(1) bond lengths are 2.42 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), two equivalent Sr(5), one Al(3), one Si(1), and one Si(3) atom. The Al(1)-Al(3) bond length is 2.59 Å. The Al(1)-Si(1) bond length is 2.51 Å. The Al(1)-Si(3) bond length is 2.49 Å. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to two equivalent Sr(1), four equivalent Sr(3), one Al(2), one Si(1), and one Si(2) atom. The Al(2)-Al(2) bond length is 2.59 Å. The Al(2)-Si(1) bond length is 2.50 Å. The Al(2)-Si(2) bond length is 2.53 Å. In the third Al site, Al(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Sr(2), two equivalent Sr(3), two equivalent Sr(4), one Al(1), one Si(2), and one Si(4) atom. The Al(3)-Si(2) bond length is 2.51 Å. The Al(3)-Si(4) bond length is 2.48 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), three equivalent Sr(5), one Al(1), and one Al(2) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Sr(6), two equivalent Sr(1), two equivalent Sr(3), two equivalent Sr(4), one Al(2), and one Al(3) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Sr(1), one Sr(7), two equivalent Sr(2), two equivalent Sr(5), two equivalent Sr(6), and one Al(1) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Sr(7), two equivalent Sr(2), two equivalent Sr(6), three equivalent Sr(4), and one Al(3) atom. O(1) is bonded to two equivalent Sr(2), two equivalent Sr(6), and two equivalent Sr(7) atoms to form corner-sharing OSr6 octahedra. The corner-sharing octahedra are not tilted.