Ba2Si5N8 is Chalcostibite-like structured and crystallizes in the orthorhombic Pmn2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one N(1), one N(6), two equivalent N(2), two equivalent N(4), and four equivalent N(5) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to one N(2), one N(3), two equivalent N(5), and two equivalent N(6) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(2), one N(3), and two equivalent N(4) atoms to form corner-sharing SiN4 tetrahedra. In the second Si site, Si(2) is bonded to one N(1), one N(6), and two equivalent N(4) atoms to form corner-sharing SiN4 tetrahedra. In the third Si site, Si(3) is bonded to one N(2), one N(6), and two equivalent N(5) atoms to form corner-sharing SiN4 tetrahedra. In the fourth Si site, Si(4) is bonded to one N(1), one N(3), one N(4), and one N(5) atom to form corner-sharing SiN4 tetrahedra. There are six inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Ba(1), one Si(2), and two equivalent Si(4) atoms. In the second N site, N(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Si(1), and one Si(3) atom. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one Ba(2), one Si(1), and two equivalent Si(4) atoms. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Ba(1), one Si(1), one Si(2), and one Si(4) atom. In the fifth N site, N(5) is bonded in a 2-coordinate geometry to one Ba(2), two equivalent Ba(1), one Si(3), and one Si(4) atom. In the sixth N site, N(6) is bonded in a distorted bent 150 degrees geometry to one Ba(1), two equivalent Ba(2), one Si(2), and one Si(3) atom.
Ba2Si5N8 is Chalcostibite-like structured and crystallizes in the orthorhombic Pmn2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one N(1), one N(6), two equivalent N(2), two equivalent N(4), and four equivalent N(5) atoms. The Ba(1)-N(1) bond length is 3.35 Å. The Ba(1)-N(6) bond length is 2.71 Å. Both Ba(1)-N(2) bond lengths are 2.94 Å. Both Ba(1)-N(4) bond lengths are 3.00 Å. There are two shorter (2.84 Å) and two longer (3.16 Å) Ba(1)-N(5) bond lengths. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to one N(2), one N(3), two equivalent N(5), and two equivalent N(6) atoms. The Ba(2)-N(2) bond length is 2.73 Å. The Ba(2)-N(3) bond length is 2.95 Å. Both Ba(2)-N(5) bond lengths are 2.77 Å. Both Ba(2)-N(6) bond lengths are 2.93 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(2), one N(3), and two equivalent N(4) atoms to form corner-sharing SiN4 tetrahedra. The Si(1)-N(2) bond length is 1.66 Å. The Si(1)-N(3) bond length is 1.75 Å. Both Si(1)-N(4) bond lengths are 1.80 Å. In the second Si site, Si(2) is bonded to one N(1), one N(6), and two equivalent N(4) atoms to form corner-sharing SiN4 tetrahedra. The Si(2)-N(1) bond length is 1.79 Å. The Si(2)-N(6) bond length is 1.67 Å. Both Si(2)-N(4) bond lengths are 1.79 Å. In the third Si site, Si(3) is bonded to one N(2), one N(6), and two equivalent N(5) atoms to form corner-sharing SiN4 tetrahedra. The Si(3)-N(2) bond length is 1.71 Å. The Si(3)-N(6) bond length is 1.73 Å. Both Si(3)-N(5) bond lengths are 1.72 Å. In the fourth Si site, Si(4) is bonded to one N(1), one N(3), one N(4), and one N(5) atom to form corner-sharing SiN4 tetrahedra. The Si(4)-N(1) bond length is 1.77 Å. The Si(4)-N(3) bond length is 1.77 Å. The Si(4)-N(4) bond length is 1.79 Å. The Si(4)-N(5) bond length is 1.69 Å. There are six inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Ba(1), one Si(2), and two equivalent Si(4) atoms. In the second N site, N(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Si(1), and one Si(3) atom. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one Ba(2), one Si(1), and two equivalent Si(4) atoms. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Ba(1), one Si(1), one Si(2), and one Si(4) atom. In the fifth N site, N(5) is bonded in a 2-coordinate geometry to one Ba(2), two equivalent Ba(1), one Si(3), and one Si(4) atom. In the sixth N site, N(6) is bonded in a distorted bent 150 degrees geometry to one Ba(1), two equivalent Ba(2), one Si(2), and one Si(3) atom.