Cs6Bi4O9 crystallizes in the triclinic P-1 space group. There are six inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 5-coordinate geometry to one O(4), one O(8), one O(9), and two equivalent O(3) atoms. In the second Cs site, Cs(2) is bonded in a 5-coordinate geometry to one O(2), one O(6), two equivalent O(1), and two equivalent O(5) atoms. In the third Cs site, Cs(3) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), one O(8), and one O(9) atom. In the fourth Cs site, Cs(4) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(6), one O(7), and two equivalent O(2) atoms. In the fifth Cs site, Cs(5) is bonded in a 6-coordinate geometry to one O(4), one O(5), one O(6), one O(7), and two equivalent O(9) atoms. In the sixth Cs site, Cs(6) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a distorted see-saw-like geometry to one O(6), one O(9), and two equivalent O(4) atoms. In the second Bi site, Bi(2) is bonded in a 3-coordinate geometry to one O(2), one O(7), and one O(8) atom. In the third Bi site, Bi(3) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(6), and one O(8) atom. In the fourth Bi site, Bi(4) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(5), and one O(7) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Cs(3), one Cs(4), one Cs(6), two equivalent Cs(2), and one Bi(4) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Cs(2), one Cs(6), two equivalent Cs(4), and one Bi(2) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Cs(3), one Cs(4), one Cs(6), two equivalent Cs(1), and one Bi(3) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Cs(1), one Cs(5), one Cs(6), one Bi(3), and two equivalent Bi(1) atoms. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Cs(3), one Cs(5), one Cs(6), two equivalent Cs(2), and one Bi(4) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Cs(2), one Cs(4), one Cs(5), one Bi(1), and one Bi(3) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Cs(4), one Cs(5), one Bi(2), and one Bi(4) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Cs(1), one Cs(3), one Bi(2), and one Bi(3) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Cs(1), one Cs(3), two equivalent Cs(5), and one Bi(1) atom.
Cs6Bi4O9 crystallizes in the triclinic P-1 space group. There are six inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 5-coordinate geometry to one O(4), one O(8), one O(9), and two equivalent O(3) atoms. The Cs(1)-O(4) bond length is 3.15 Å. The Cs(1)-O(8) bond length is 3.00 Å. The Cs(1)-O(9) bond length is 2.93 Å. There is one shorter (3.01 Å) and one longer (3.07 Å) Cs(1)-O(3) bond length. In the second Cs site, Cs(2) is bonded in a 5-coordinate geometry to one O(2), one O(6), two equivalent O(1), and two equivalent O(5) atoms. The Cs(2)-O(2) bond length is 3.21 Å. The Cs(2)-O(6) bond length is 3.28 Å. There is one shorter (3.23 Å) and one longer (3.65 Å) Cs(2)-O(1) bond length. There is one shorter (3.07 Å) and one longer (3.29 Å) Cs(2)-O(5) bond length. In the third Cs site, Cs(3) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), one O(8), and one O(9) atom. The Cs(3)-O(1) bond length is 2.85 Å. The Cs(3)-O(3) bond length is 3.12 Å. The Cs(3)-O(5) bond length is 3.15 Å. The Cs(3)-O(8) bond length is 3.15 Å. The Cs(3)-O(9) bond length is 2.96 Å. In the fourth Cs site, Cs(4) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(6), one O(7), and two equivalent O(2) atoms. The Cs(4)-O(1) bond length is 3.21 Å. The Cs(4)-O(3) bond length is 3.03 Å. The Cs(4)-O(6) bond length is 3.11 Å. The Cs(4)-O(7) bond length is 3.10 Å. Both Cs(4)-O(2) bond lengths are 3.23 Å. In the fifth Cs site, Cs(5) is bonded in a 6-coordinate geometry to one O(4), one O(5), one O(6), one O(7), and two equivalent O(9) atoms. The Cs(5)-O(4) bond length is 3.20 Å. The Cs(5)-O(5) bond length is 3.00 Å. The Cs(5)-O(6) bond length is 3.31 Å. The Cs(5)-O(7) bond length is 3.04 Å. There is one shorter (2.97 Å) and one longer (3.18 Å) Cs(5)-O(9) bond length. In the sixth Cs site, Cs(6) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. The Cs(6)-O(1) bond length is 3.28 Å. The Cs(6)-O(2) bond length is 2.92 Å. The Cs(6)-O(3) bond length is 3.47 Å. The Cs(6)-O(4) bond length is 3.54 Å. The Cs(6)-O(5) bond length is 3.08 Å. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a distorted see-saw-like geometry to one O(6), one O(9), and two equivalent O(4) atoms. The Bi(1)-O(6) bond length is 2.29 Å. The Bi(1)-O(9) bond length is 2.04 Å. There is one shorter (2.11 Å) and one longer (2.48 Å) Bi(1)-O(4) bond length. In the second Bi site, Bi(2) is bonded in a 3-coordinate geometry to one O(2), one O(7), and one O(8) atom. The Bi(2)-O(2) bond length is 2.03 Å. The Bi(2)-O(7) bond length is 2.13 Å. The Bi(2)-O(8) bond length is 2.10 Å. In the third Bi site, Bi(3) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(6), and one O(8) atom. The Bi(3)-O(3) bond length is 2.04 Å. The Bi(3)-O(4) bond length is 2.74 Å. The Bi(3)-O(6) bond length is 2.10 Å. The Bi(3)-O(8) bond length is 2.21 Å. In the fourth Bi site, Bi(4) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(5), and one O(7) atom. The Bi(4)-O(1) bond length is 2.04 Å. The Bi(4)-O(5) bond length is 2.05 Å. The Bi(4)-O(7) bond length is 2.17 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Cs(3), one Cs(4), one Cs(6), two equivalent Cs(2), and one Bi(4) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Cs(2), one Cs(6), two equivalent Cs(4), and one Bi(2) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Cs(3), one Cs(4), one Cs(6), two equivalent Cs(1), and one Bi(3) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Cs(1), one Cs(5), one Cs(6), one Bi(3), and two equivalent Bi(1) atoms. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Cs(3), one Cs(5), one Cs(6), two equivalent Cs(2), and one Bi(4) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Cs(2), one Cs(4), one Cs(5), one Bi(1), and one Bi(3) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Cs(4), one Cs(5), one Bi(2), and one Bi(4) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Cs(1), one Cs(3), one Bi(2), and one Bi(3) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Cs(1), one Cs(3), two equivalent Cs(5), and one Bi(1) atom.