Sr2Al7Ge crystallizes in the tetragonal P4mm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 16-coordinate geometry to four equivalent Al(1), four equivalent Al(2), four equivalent Al(5), and four equivalent Ge(1) atoms. In the second Sr site, Sr(2) is bonded in a 16-coordinate geometry to four equivalent Al(1), four equivalent Al(2), four equivalent Al(3), and four equivalent Al(4) atoms. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded in a 2-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Al(4), and two equivalent Ge(1) atoms. In the second Al site, Al(2) is bonded in a 8-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Al(3), and two equivalent Al(5) atoms. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to four equivalent Sr(2), one Al(4), and four equivalent Al(2) atoms. In the fourth Al site, Al(4) is bonded in a 9-coordinate geometry to four equivalent Sr(2), one Al(3), and four equivalent Al(1) atoms. In the fifth Al site, Al(5) is bonded in a distorted single-bond geometry to four equivalent Sr(1), four equivalent Al(2), and one Ge(1) atom. Ge(1) is bonded in a 9-coordinate geometry to four equivalent Sr(1), one Al(5), and four equivalent Al(1) atoms.
Sr2Al7Ge crystallizes in the tetragonal P4mm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 16-coordinate geometry to four equivalent Al(1), four equivalent Al(2), four equivalent Al(5), and four equivalent Ge(1) atoms. All Sr(1)-Al(1) bond lengths are 3.57 Å. All Sr(1)-Al(2) bond lengths are 3.55 Å. All Sr(1)-Al(5) bond lengths are 3.42 Å. All Sr(1)-Ge(1) bond lengths are 3.42 Å. In the second Sr site, Sr(2) is bonded in a 16-coordinate geometry to four equivalent Al(1), four equivalent Al(2), four equivalent Al(3), and four equivalent Al(4) atoms. All Sr(2)-Al(1) bond lengths are 3.57 Å. All Sr(2)-Al(2) bond lengths are 3.55 Å. All Sr(2)-Al(3) bond lengths are 3.42 Å. All Sr(2)-Al(4) bond lengths are 3.43 Å. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded in a 2-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Al(4), and two equivalent Ge(1) atoms. Both Al(1)-Al(4) bond lengths are 2.66 Å. Both Al(1)-Ge(1) bond lengths are 2.68 Å. In the second Al site, Al(2) is bonded in a 8-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), two equivalent Al(3), and two equivalent Al(5) atoms. Both Al(2)-Al(3) bond lengths are 2.67 Å. Both Al(2)-Al(5) bond lengths are 2.67 Å. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to four equivalent Sr(2), one Al(4), and four equivalent Al(2) atoms. The Al(3)-Al(4) bond length is 2.63 Å. In the fourth Al site, Al(4) is bonded in a 9-coordinate geometry to four equivalent Sr(2), one Al(3), and four equivalent Al(1) atoms. In the fifth Al site, Al(5) is bonded in a distorted single-bond geometry to four equivalent Sr(1), four equivalent Al(2), and one Ge(1) atom. The Al(5)-Ge(1) bond length is 2.61 Å. Ge(1) is bonded in a 9-coordinate geometry to four equivalent Sr(1), one Al(5), and four equivalent Al(1) atoms.