Eu3O4Br crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), three equivalent O(3), and two equivalent Br(1) atoms. In the second Eu site, Eu(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Eu(1) and two equivalent Eu(2) atoms to form a mixture of corner and edge-sharing OEu4 tetrahedra. In the second O site, O(2) is bonded in a trigonal planar geometry to one Eu(2) and two equivalent Eu(1) atoms. In the third O site, O(3) is bonded to one Eu(2) and three equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing OEu4 tetrahedra. Br(1) is bonded in a square co-planar geometry to four equivalent Eu(1) atoms.
Eu3O4Br crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), three equivalent O(3), and two equivalent Br(1) atoms. The Eu(1)-O(1) bond length is 2.33 Å. The Eu(1)-O(2) bond length is 2.24 Å. There is one shorter (2.31 Å) and two longer (2.34 Å) Eu(1)-O(3) bond lengths. Both Eu(1)-Br(1) bond lengths are 3.21 Å. In the second Eu site, Eu(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. The Eu(2)-O(2) bond length is 2.28 Å. Both Eu(2)-O(1) bond lengths are 2.27 Å. Both Eu(2)-O(3) bond lengths are 2.33 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Eu(1) and two equivalent Eu(2) atoms to form a mixture of corner and edge-sharing OEu4 tetrahedra. In the second O site, O(2) is bonded in a trigonal planar geometry to one Eu(2) and two equivalent Eu(1) atoms. In the third O site, O(3) is bonded to one Eu(2) and three equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing OEu4 tetrahedra. Br(1) is bonded in a square co-planar geometry to four equivalent Eu(1) atoms.