Bi4O5 crystallizes in the monoclinic Cc space group. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a T-shaped geometry to one O(1), one O(3), and one O(4) atom. In the second Bi site, Bi(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted BiO5 square pyramids that share  a cornercorner with one Bi(3)O5 square pyramid,  a cornercorner with one Bi(4)O4 trigonal pyramid, edges with two equivalent Bi(2)O5 square pyramids, and edges with two equivalent Bi(3)O5 square pyramids. In the third Bi site, Bi(3) is bonded to one O(1), two equivalent O(2), and two equivalent O(5) atoms to form distorted BiO5 square pyramids that share  a cornercorner with one Bi(2)O5 square pyramid, corners with three equivalent Bi(4)O4 trigonal pyramids, edges with two equivalent Bi(2)O5 square pyramids, and edges with two equivalent Bi(3)O5 square pyramids. In the fourth Bi site, Bi(4) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form distorted BiO4 trigonal pyramids that share  a cornercorner with one Bi(2)O5 square pyramid, corners with three equivalent Bi(3)O5 square pyramids, and corners with two equivalent Bi(4)O4 trigonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Bi(1), one Bi(2), one Bi(3), and one Bi(4) atom to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the second O site, O(2) is bonded to two equivalent Bi(2) and two equivalent Bi(3) atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Bi(1) and two equivalent Bi(4) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Bi(1) and two equivalent Bi(2) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Bi(4) and two equivalent Bi(3) atoms.
Bi4O5 crystallizes in the monoclinic Cc space group. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a T-shaped geometry to one O(1), one O(3), and one O(4) atom. The Bi(1)-O(1) bond length is 2.43 Å. The Bi(1)-O(3) bond length is 2.25 Å. The Bi(1)-O(4) bond length is 2.35 Å. In the second Bi site, Bi(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted BiO5 square pyramids that share  a cornercorner with one Bi(3)O5 square pyramid,  a cornercorner with one Bi(4)O4 trigonal pyramid, edges with two equivalent Bi(2)O5 square pyramids, and edges with two equivalent Bi(3)O5 square pyramids. The Bi(2)-O(1) bond length is 2.38 Å. There is one shorter (2.23 Å) and one longer (2.53 Å) Bi(2)-O(2) bond length. There is one shorter (2.18 Å) and one longer (2.31 Å) Bi(2)-O(4) bond length. In the third Bi site, Bi(3) is bonded to one O(1), two equivalent O(2), and two equivalent O(5) atoms to form distorted BiO5 square pyramids that share  a cornercorner with one Bi(2)O5 square pyramid, corners with three equivalent Bi(4)O4 trigonal pyramids, edges with two equivalent Bi(2)O5 square pyramids, and edges with two equivalent Bi(3)O5 square pyramids. The Bi(3)-O(1) bond length is 2.35 Å. There is one shorter (2.27 Å) and one longer (2.45 Å) Bi(3)-O(2) bond length. There is one shorter (2.28 Å) and one longer (2.32 Å) Bi(3)-O(5) bond length. In the fourth Bi site, Bi(4) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form distorted BiO4 trigonal pyramids that share  a cornercorner with one Bi(2)O5 square pyramid, corners with three equivalent Bi(3)O5 square pyramids, and corners with two equivalent Bi(4)O4 trigonal pyramids. The Bi(4)-O(1) bond length is 2.42 Å. The Bi(4)-O(5) bond length is 2.42 Å. There is one shorter (2.15 Å) and one longer (2.32 Å) Bi(4)-O(3) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Bi(1), one Bi(2), one Bi(3), and one Bi(4) atom to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the second O site, O(2) is bonded to two equivalent Bi(2) and two equivalent Bi(3) atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Bi(1) and two equivalent Bi(4) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Bi(1) and two equivalent Bi(2) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Bi(4) and two equivalent Bi(3) atoms.