Ba11(SiN5)2 crystallizes in the tetragonal P4_2/mnm space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent N(4) and four equivalent N(1) atoms to form a mixture of corner and edge-sharing BaN6 octahedra. The corner-sharing octahedral tilt angles are 5°. In the second Ba site, Ba(2) is bonded in a 5-coordinate geometry to one N(1), two equivalent N(2), and two equivalent N(4) atoms. In the third Ba site, Ba(3) is bonded to two equivalent N(1), two equivalent N(2), and two equivalent N(3) atoms to form a mixture of distorted corner and edge-sharing BaN6 octahedra. The corner-sharing octahedral tilt angles are 5°. In the fourth Ba site, Ba(4) is bonded in a 4-coordinate geometry to one N(3) and three equivalent N(2) atoms. Si(1) is bonded in a linear geometry to one N(3) and one N(4) atom. There are four inequivalent N sites. In the first N site, N(3) is bonded to two equivalent Ba(3), two equivalent Ba(4), and one Si(1) atom to form distorted NBa4Si trigonal bipyramids that share  a cornercorner with one N(4)Ba5Si octahedra, corners with two equivalent N(1)Ba6 octahedra, corners with two equivalent N(3)Ba4Si trigonal bipyramids, and  an edgeedge with one N(1)Ba6 octahedra. The corner-sharing octahedra are not tilted. In the second N site, N(4) is bonded to one Ba(1), four equivalent Ba(2), and one Si(1) atom to form distorted NBa5Si octahedra that share  a cornercorner with one N(4)Ba5Si octahedra,  a cornercorner with one N(3)Ba4Si trigonal bipyramid, edges with two equivalent N(4)Ba5Si octahedra, and edges with four equivalent N(1)Ba6 octahedra. The corner-sharing octahedra are not tilted. In the third N site, N(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Ba(3) atoms to form NBa6 octahedra that share corners with two equivalent N(1)Ba6 octahedra, corners with two equivalent N(3)Ba4Si trigonal bipyramids, edges with three equivalent N(1)Ba6 octahedra, edges with four equivalent N(4)Ba5Si octahedra, and  an edgeedge with one N(3)Ba4Si trigonal bipyramid. The corner-sharing octahedra are not tilted. In the fourth N site, N(2) is bonded in a 6-coordinate geometry to one Ba(3), two equivalent Ba(2), and three equivalent Ba(4) atoms.
Ba11(SiN5)2 crystallizes in the tetragonal P4_2/mnm space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent N(4) and four equivalent N(1) atoms to form a mixture of corner and edge-sharing BaN6 octahedra. The corner-sharing octahedral tilt angles are 5°. Both Ba(1)-N(4) bond lengths are 2.83 Å. All Ba(1)-N(1) bond lengths are 3.04 Å. In the second Ba site, Ba(2) is bonded in a 5-coordinate geometry to one N(1), two equivalent N(2), and two equivalent N(4) atoms. The Ba(2)-N(1) bond length is 2.67 Å. Both Ba(2)-N(2) bond lengths are 2.88 Å. Both Ba(2)-N(4) bond lengths are 3.06 Å. In the third Ba site, Ba(3) is bonded to two equivalent N(1), two equivalent N(2), and two equivalent N(3) atoms to form a mixture of distorted corner and edge-sharing BaN6 octahedra. The corner-sharing octahedral tilt angles are 5°. Both Ba(3)-N(1) bond lengths are 2.79 Å. Both Ba(3)-N(2) bond lengths are 3.45 Å. Both Ba(3)-N(3) bond lengths are 2.77 Å. In the fourth Ba site, Ba(4) is bonded in a 4-coordinate geometry to one N(3) and three equivalent N(2) atoms. The Ba(4)-N(3) bond length is 3.24 Å. There are two shorter (2.73 Å) and one longer (2.82 Å) Ba(4)-N(2) bond length. Si(1) is bonded in a linear geometry to one N(3) and one N(4) atom. The Si(1)-N(3) bond length is 1.62 Å. The Si(1)-N(4) bond length is 1.63 Å. There are four inequivalent N sites. In the first N site, N(3) is bonded to two equivalent Ba(3), two equivalent Ba(4), and one Si(1) atom to form distorted NBa4Si trigonal bipyramids that share  a cornercorner with one N(4)Ba5Si octahedra, corners with two equivalent N(1)Ba6 octahedra, corners with two equivalent N(3)Ba4Si trigonal bipyramids, and  an edgeedge with one N(1)Ba6 octahedra. The corner-sharing octahedra are not tilted. In the second N site, N(4) is bonded to one Ba(1), four equivalent Ba(2), and one Si(1) atom to form distorted NBa5Si octahedra that share  a cornercorner with one N(4)Ba5Si octahedra,  a cornercorner with one N(3)Ba4Si trigonal bipyramid, edges with two equivalent N(4)Ba5Si octahedra, and edges with four equivalent N(1)Ba6 octahedra. The corner-sharing octahedra are not tilted. In the third N site, N(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Ba(3) atoms to form NBa6 octahedra that share corners with two equivalent N(1)Ba6 octahedra, corners with two equivalent N(3)Ba4Si trigonal bipyramids, edges with three equivalent N(1)Ba6 octahedra, edges with four equivalent N(4)Ba5Si octahedra, and  an edgeedge with one N(3)Ba4Si trigonal bipyramid. The corner-sharing octahedra are not tilted. In the fourth N site, N(2) is bonded in a 6-coordinate geometry to one Ba(3), two equivalent Ba(2), and three equivalent Ba(4) atoms.