Ba2SrB18 is Calcium hexaboride-derived structured and crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 24-coordinate geometry to four equivalent B(3), four equivalent B(4), eight equivalent B(1), and eight equivalent B(2) atoms. Sr(1) is bonded in a 24-coordinate geometry to eight equivalent B(5) and sixteen equivalent B(1) atoms. There are five inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to two equivalent Ba(1), two equivalent Sr(1), one B(3), one B(5), and three equivalent B(1) atoms. In the second B site, B(2) is bonded in a 9-coordinate geometry to four equivalent Ba(1), two equivalent B(4), and three equivalent B(2) atoms. In the third B site, B(3) is bonded in a 9-coordinate geometry to four equivalent Ba(1), one B(4), and four equivalent B(1) atoms. In the fourth B site, B(4) is bonded in a 9-coordinate geometry to four equivalent Ba(1), one B(3), and four equivalent B(2) atoms. In the fifth B site, B(5) is bonded in a 5-coordinate geometry to four equivalent Sr(1), one B(5), and four equivalent B(1) atoms.
Ba2SrB18 is Calcium hexaboride-derived structured and crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 24-coordinate geometry to four equivalent B(3), four equivalent B(4), eight equivalent B(1), and eight equivalent B(2) atoms. All Ba(1)-B(3) bond lengths are 3.13 Å. All Ba(1)-B(4) bond lengths are 3.13 Å. All Ba(1)-B(1) bond lengths are 3.14 Å. All Ba(1)-B(2) bond lengths are 3.13 Å. Sr(1) is bonded in a 24-coordinate geometry to eight equivalent B(5) and sixteen equivalent B(1) atoms. All Sr(1)-B(5) bond lengths are 3.13 Å. All Sr(1)-B(1) bond lengths are 3.12 Å. There are five inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to two equivalent Ba(1), two equivalent Sr(1), one B(3), one B(5), and three equivalent B(1) atoms. The B(1)-B(3) bond length is 1.78 Å. The B(1)-B(5) bond length is 1.78 Å. There is one shorter (1.74 Å) and two longer (1.78 Å) B(1)-B(1) bond lengths. In the second B site, B(2) is bonded in a 9-coordinate geometry to four equivalent Ba(1), two equivalent B(4), and three equivalent B(2) atoms. Both B(2)-B(4) bond lengths are 1.78 Å. There is one shorter (1.74 Å) and two longer (1.78 Å) B(2)-B(2) bond lengths. In the third B site, B(3) is bonded in a 9-coordinate geometry to four equivalent Ba(1), one B(4), and four equivalent B(1) atoms. The B(3)-B(4) bond length is 1.75 Å. In the fourth B site, B(4) is bonded in a 9-coordinate geometry to four equivalent Ba(1), one B(3), and four equivalent B(2) atoms. In the fifth B site, B(5) is bonded in a 5-coordinate geometry to four equivalent Sr(1), one B(5), and four equivalent B(1) atoms. The B(5)-B(5) bond length is 1.72 Å.