Fe2B2O5 crystallizes in the triclinic P-1 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), two equivalent O(3), and three equivalent O(2) atoms to form edge-sharing FeO6 octahedra. In the second Fe site, Fe(2) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted edge-sharing FeO6 octahedra. 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(5) atom. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(3), 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 4-coordinate geometry to one Fe(1), two equivalent Fe(2), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Fe(1) and one B(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Fe(2), two equivalent Fe(1), and one B(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Fe(2) and one B(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Fe(2), one B(1), and one B(2) atom.
Fe2B2O5 crystallizes in the triclinic P-1 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), two equivalent O(3), and three equivalent O(2) atoms to form edge-sharing FeO6 octahedra. The Fe(1)-O(1) bond length is 2.01 Å. There is one shorter (2.17 Å) and one longer (2.18 Å) Fe(1)-O(3) bond length. There are a spread of Fe(1)-O(2) bond distances ranging from 2.13-2.16 Å. In the second Fe site, Fe(2) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted edge-sharing FeO6 octahedra. The Fe(2)-O(3) bond length is 2.08 Å. The Fe(2)-O(5) bond length is 2.15 Å. There is one shorter (2.29 Å) and one longer (2.33 Å) Fe(2)-O(1) bond length. There is one shorter (1.99 Å) and one longer (2.08 Å) Fe(2)-O(4) bond length. 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(5) atom. The B(1)-O(1) bond length is 1.36 Å. The B(1)-O(2) bond length is 1.36 Å. The B(1)-O(5) bond length is 1.42 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(3), one O(4), and one O(5) atom. The B(2)-O(3) bond length is 1.36 Å. The B(2)-O(4) bond length is 1.35 Å. The B(2)-O(5) bond length is 1.42 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Fe(1), two equivalent Fe(2), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Fe(1) and one B(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Fe(2), two equivalent Fe(1), and one B(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Fe(2) and one B(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Fe(2), one B(1), and one B(2) atom.