Sr3(AlN2)2 crystallizes in the orthorhombic Pnna space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to two equivalent N(1) and four equivalent N(2) atoms. In the second Sr site, Sr(2) is bonded in a 4-coordinate geometry to one N(2) and three equivalent N(1) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form distorted edge-sharing AlN4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form edge-sharing AlN4 tetrahedra. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 6-coordinate geometry to one Sr(1), three equivalent Sr(2), one Al(1), and one Al(2) atom. In the second N site, N(2) is bonded in a 5-coordinate geometry to one Sr(2), two equivalent Sr(1), one Al(1), and one Al(2) atom.
Sr3(AlN2)2 crystallizes in the orthorhombic Pnna space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to two equivalent N(1) and four equivalent N(2) atoms. Both Sr(1)-N(1) bond lengths are 2.94 Å. There are two shorter (2.68 Å) and two longer (2.70 Å) Sr(1)-N(2) bond lengths. In the second Sr site, Sr(2) is bonded in a 4-coordinate geometry to one N(2) and three equivalent N(1) atoms. The Sr(2)-N(2) bond length is 2.51 Å. There are a spread of Sr(2)-N(1) bond distances ranging from 2.58-2.77 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form distorted edge-sharing AlN4 tetrahedra. Both Al(1)-N(1) bond lengths are 1.92 Å. Both Al(1)-N(2) bond lengths are 1.95 Å. In the second Al site, Al(2) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form edge-sharing AlN4 tetrahedra. Both Al(2)-N(1) bond lengths are 1.92 Å. Both Al(2)-N(2) bond lengths are 1.89 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 6-coordinate geometry to one Sr(1), three equivalent Sr(2), one Al(1), and one Al(2) atom. In the second N site, N(2) is bonded in a 5-coordinate geometry to one Sr(2), two equivalent Sr(1), one Al(1), and one Al(2) atom.