BaAlSi5O2N7 crystallizes in the triclinic P1 space group. Ba(1) is bonded in a 2-coordinate geometry to one N(7) and one O(2) atom. Al(1) is bonded to one N(1), one N(2), one N(5), and one O(2) atom to form AlN3O tetrahedra that share  a cornercorner with one Si(2)N3O tetrahedra,  a cornercorner with one Si(5)N3O tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, corners with two equivalent Si(1)N3O tetrahedra, and corners with two equivalent Si(3)N4 tetrahedra. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(1), one N(3), one N(5), and one O(1) atom to form SiN3O tetrahedra that share  a cornercorner with one Si(2)N3O tetrahedra,  a cornercorner with one Si(5)N3O tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, corners with two equivalent Al(1)N3O tetrahedra, and corners with two equivalent Si(4)N4 tetrahedra. In the second Si site, Si(2) is bonded to one N(2), one N(4), one N(6), and one O(1) atom to form SiN3O tetrahedra that share  a cornercorner with one Al(1)N3O tetrahedra,  a cornercorner with one Si(1)N3O tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, corners with two equivalent Si(5)N3O tetrahedra, and corners with two equivalent Si(3)N4 tetrahedra. In the third Si site, Si(3) is bonded to one N(1), one N(2), one N(6), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Si(1)N3O tetrahedra,  a cornercorner with one Si(5)N3O tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, corners with two equivalent Al(1)N3O tetrahedra, and corners with two equivalent Si(2)N3O tetrahedra. In the fourth Si site, Si(4) is bonded to one N(3), one N(4), one N(5), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N3O tetrahedra,  a cornercorner with one Si(2)N3O tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, corners with two equivalent Si(1)N3O tetrahedra, and corners with two equivalent Si(5)N3O tetrahedra. In the fifth Si site, Si(5) is bonded to one N(3), one N(4), one N(6), and one O(2) atom to form SiN3O tetrahedra that share  a cornercorner with one Al(1)N3O tetrahedra,  a cornercorner with one Si(1)N3O tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, corners with two equivalent Si(2)N3O tetrahedra, and corners with two equivalent Si(4)N4 tetrahedra. There are seven inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one Al(1), one Si(1), and one Si(3) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one Al(1), one Si(2), and one Si(3) atom. In the third N site, N(3) is bonded in a trigonal planar geometry to one Si(1), one Si(4), and one Si(5) atom. In the fourth N site, N(4) is bonded in a trigonal planar geometry to one Si(2), one Si(4), and one Si(5) atom. In the fifth N site, N(5) is bonded in a distorted trigonal planar geometry to one Al(1), one Si(1), and one Si(4) atom. In the sixth N site, N(6) is bonded in a distorted trigonal planar geometry to one Si(2), one Si(3), and one Si(5) atom. In the seventh N site, N(7) is bonded in a 2-coordinate geometry to one Ba(1), one Si(3), and one Si(4) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Al(1), and one Si(5) atom.
BaAlSi5O2N7 crystallizes in the triclinic P1 space group. Ba(1) is bonded in a 2-coordinate geometry to one N(7) and one O(2) atom. The Ba(1)-N(7) bond length is 2.78 Å. The Ba(1)-O(2) bond length is 2.92 Å. Al(1) is bonded to one N(1), one N(2), one N(5), and one O(2) atom to form AlN3O tetrahedra that share  a cornercorner with one Si(2)N3O tetrahedra,  a cornercorner with one Si(5)N3O tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, corners with two equivalent Si(1)N3O tetrahedra, and corners with two equivalent Si(3)N4 tetrahedra. The Al(1)-N(1) bond length is 1.85 Å. The Al(1)-N(2) bond length is 1.85 Å. The Al(1)-N(5) bond length is 1.87 Å. The Al(1)-O(2) bond length is 1.79 Å. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(1), one N(3), one N(5), and one O(1) atom to form SiN3O tetrahedra that share  a cornercorner with one Si(2)N3O tetrahedra,  a cornercorner with one Si(5)N3O tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, corners with two equivalent Al(1)N3O tetrahedra, and corners with two equivalent Si(4)N4 tetrahedra. The Si(1)-N(1) bond length is 1.72 Å. The Si(1)-N(3) bond length is 1.76 Å. The Si(1)-N(5) bond length is 1.71 Å. The Si(1)-O(1) bond length is 1.65 Å. In the second Si site, Si(2) is bonded to one N(2), one N(4), one N(6), and one O(1) atom to form SiN3O tetrahedra that share  a cornercorner with one Al(1)N3O tetrahedra,  a cornercorner with one Si(1)N3O tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, corners with two equivalent Si(5)N3O tetrahedra, and corners with two equivalent Si(3)N4 tetrahedra. The Si(2)-N(2) bond length is 1.71 Å. The Si(2)-N(4) bond length is 1.74 Å. The Si(2)-N(6) bond length is 1.74 Å. The Si(2)-O(1) bond length is 1.63 Å. In the third Si site, Si(3) is bonded to one N(1), one N(2), one N(6), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Si(1)N3O tetrahedra,  a cornercorner with one Si(5)N3O tetrahedra,  a cornercorner with one Si(4)N4 tetrahedra, corners with two equivalent Al(1)N3O tetrahedra, and corners with two equivalent Si(2)N3O tetrahedra. The Si(3)-N(1) bond length is 1.74 Å. The Si(3)-N(2) bond length is 1.75 Å. The Si(3)-N(6) bond length is 1.83 Å. The Si(3)-N(7) bond length is 1.70 Å. In the fourth Si site, Si(4) is bonded to one N(3), one N(4), one N(5), and one N(7) atom to form SiN4 tetrahedra that share  a cornercorner with one Al(1)N3O tetrahedra,  a cornercorner with one Si(2)N3O tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, corners with two equivalent Si(1)N3O tetrahedra, and corners with two equivalent Si(5)N3O tetrahedra. The Si(4)-N(3) bond length is 1.79 Å. The Si(4)-N(4) bond length is 1.76 Å. The Si(4)-N(5) bond length is 1.75 Å. The Si(4)-N(7) bond length is 1.70 Å. In the fifth Si site, Si(5) is bonded to one N(3), one N(4), one N(6), and one O(2) atom to form SiN3O tetrahedra that share  a cornercorner with one Al(1)N3O tetrahedra,  a cornercorner with one Si(1)N3O tetrahedra,  a cornercorner with one Si(3)N4 tetrahedra, corners with two equivalent Si(2)N3O tetrahedra, and corners with two equivalent Si(4)N4 tetrahedra. The Si(5)-N(3) bond length is 1.73 Å. The Si(5)-N(4) bond length is 1.75 Å. The Si(5)-N(6) bond length is 1.77 Å. The Si(5)-O(2) bond length is 1.66 Å. There are seven inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one Al(1), one Si(1), and one Si(3) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one Al(1), one Si(2), and one Si(3) atom. In the third N site, N(3) is bonded in a trigonal planar geometry to one Si(1), one Si(4), and one Si(5) atom. In the fourth N site, N(4) is bonded in a trigonal planar geometry to one Si(2), one Si(4), and one Si(5) atom. In the fifth N site, N(5) is bonded in a distorted trigonal planar geometry to one Al(1), one Si(1), and one Si(4) atom. In the sixth N site, N(6) is bonded in a distorted trigonal planar geometry to one Si(2), one Si(3), and one Si(5) atom. In the seventh N site, N(7) is bonded in a 2-coordinate geometry to one Ba(1), one Si(3), and one Si(4) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Al(1), and one Si(5) atom.