Ba3Si6O9N4 crystallizes in the trigonal P3 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one N(1), three equivalent O(2), and three equivalent O(3) atoms. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(3) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent N(2), one O(1), and one O(3) atom to form corner-sharing SiN2O2 tetrahedra. In the second Si site, Si(2) is bonded to one N(1), one N(2), one O(1), and one O(2) atom to form corner-sharing SiN2O2 tetrahedra. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Ba(2) and three equivalent Si(2) atoms. In the second N site, N(2) is bonded in a trigonal planar geometry to one Si(2) and two equivalent Si(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one Si(1) atom.
Ba3Si6O9N4 crystallizes in the trigonal P3 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(3) atoms. All Ba(1)-O(2) bond lengths are 2.74 Å. All Ba(1)-O(3) bond lengths are 2.76 Å. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one N(1), three equivalent O(2), and three equivalent O(3) atoms. The Ba(2)-N(1) bond length is 3.21 Å. All Ba(2)-O(2) bond lengths are 2.74 Å. All Ba(2)-O(3) bond lengths are 2.87 Å. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(3) atoms. All Ba(3)-O(2) bond lengths are 2.73 Å. All Ba(3)-O(3) bond lengths are 2.85 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent N(2), one O(1), and one O(3) atom to form corner-sharing SiN2O2 tetrahedra. There is one shorter (1.75 Å) and one longer (1.77 Å) Si(1)-N(2) bond length. The Si(1)-O(1) bond length is 1.67 Å. The Si(1)-O(3) bond length is 1.61 Å. In the second Si site, Si(2) is bonded to one N(1), one N(2), one O(1), and one O(2) atom to form corner-sharing SiN2O2 tetrahedra. The Si(2)-N(1) bond length is 1.76 Å. The Si(2)-N(2) bond length is 1.75 Å. The Si(2)-O(1) bond length is 1.67 Å. The Si(2)-O(2) bond length is 1.62 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Ba(2) and three equivalent Si(2) atoms. In the second N site, N(2) is bonded in a trigonal planar geometry to one Si(2) and two equivalent Si(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one Si(1) atom.