Eu2Os3B5 crystallizes in the monoclinic C2 space group. Eu(1) is bonded in a 2-coordinate geometry to two equivalent Os(2), two equivalent B(1), and three equivalent B(3) atoms. There are two inequivalent Os sites. In the first Os site, Os(1) is bonded in a 5-coordinate geometry to one B(1), one B(3), and three equivalent B(2) atoms. In the second Os site, Os(2) is bonded in a 10-coordinate geometry to four equivalent Eu(1), two equivalent B(2), and four equivalent B(3) atoms. There are three inequivalent B sites. In the first B site, B(1) is bonded to four equivalent Eu(1) and two equivalent Os(1) atoms to form edge-sharing BEu4Os2 octahedra. In the second B site, B(2) is bonded in a 5-coordinate geometry to one Os(2), three equivalent Os(1), and one B(3) atom. In the third B site, B(3) is bonded in a 8-coordinate geometry to three equivalent Eu(1), one Os(1), two equivalent Os(2), one B(2), and one B(3) atom.
Eu2Os3B5 crystallizes in the monoclinic C2 space group. Eu(1) is bonded in a 2-coordinate geometry to two equivalent Os(2), two equivalent B(1), and three equivalent B(3) atoms. There is one shorter (3.16 Å) and one longer (3.36 Å) Eu(1)-Os(2) bond length. There is one shorter (2.72 Å) and one longer (2.75 Å) Eu(1)-B(1) bond length. There are a spread of Eu(1)-B(3) bond distances ranging from 2.92-3.35 Å. There are two inequivalent Os sites. In the first Os site, Os(1) is bonded in a 5-coordinate geometry to one B(1), one B(3), and three equivalent B(2) atoms. The Os(1)-B(1) bond length is 1.97 Å. The Os(1)-B(3) bond length is 2.11 Å. There are a spread of Os(1)-B(2) bond distances ranging from 2.13-2.25 Å. In the second Os site, Os(2) is bonded in a 10-coordinate geometry to four equivalent Eu(1), two equivalent B(2), and four equivalent B(3) atoms. Both Os(2)-B(2) bond lengths are 2.24 Å. There are two shorter (2.17 Å) and two longer (2.22 Å) Os(2)-B(3) bond lengths. There are three inequivalent B sites. In the first B site, B(1) is bonded to four equivalent Eu(1) and two equivalent Os(1) atoms to form edge-sharing BEu4Os2 octahedra. In the second B site, B(2) is bonded in a 5-coordinate geometry to one Os(2), three equivalent Os(1), and one B(3) atom. The B(2)-B(3) bond length is 1.74 Å. In the third B site, B(3) is bonded in a 8-coordinate geometry to three equivalent Eu(1), one Os(1), two equivalent Os(2), one B(2), and one B(3) atom. The B(3)-B(3) bond length is 1.67 Å.