Ba2B2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(4), and three equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(3), and three equivalent O(5) atoms. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(2), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Ba(1) and one B(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(2), one B(1), and one B(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ba(1), two equivalent Ba(2), and one B(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one B(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to three equivalent Ba(2) and one B(2) atom.
Ba2B2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(4), and three equivalent O(1) atoms. The Ba(1)-O(3) bond length is 2.63 Å. There is one shorter (2.67 Å) and one longer (2.76 Å) Ba(1)-O(4) bond length. There are a spread of Ba(1)-O(1) bond distances ranging from 2.69-2.81 Å. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(3), and three equivalent O(5) atoms. The Ba(2)-O(4) bond length is 2.92 Å. There is one shorter (2.82 Å) and one longer (3.06 Å) Ba(2)-O(2) bond length. There is one shorter (2.73 Å) and one longer (2.89 Å) Ba(2)-O(3) bond length. There is one shorter (2.64 Å) and two longer (2.76 Å) Ba(2)-O(5) bond lengths. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The B(1)-O(1) bond length is 1.36 Å. The B(1)-O(2) bond length is 1.44 Å. The B(1)-O(3) bond length is 1.36 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(2), one O(4), and one O(5) atom. The B(2)-O(2) bond length is 1.44 Å. The B(2)-O(4) bond length is 1.35 Å. The B(2)-O(5) bond length is 1.36 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Ba(1) and one B(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(2), one B(1), and one B(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ba(1), two equivalent Ba(2), and one B(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one B(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to three equivalent Ba(2) and one B(2) atom.