Ca(BiO2)4 crystallizes in the monoclinic Cm space group. Ca(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted BiO5 square pyramids that share corners with two equivalent Bi(3)O6 octahedra and edges with two equivalent Bi(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 52°. In the second Bi site, Bi(2) is bonded in a 6-coordinate geometry to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms. In the third Bi site, Bi(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form BiO6 octahedra that share corners with two equivalent Bi(1)O5 square pyramids, corners with two equivalent Bi(4)O5 square pyramids, and edges with two equivalent Bi(3)O6 octahedra. In the fourth Bi site, Bi(4) is bonded to one O(3), two equivalent O(1), and two equivalent O(7) atoms to form BiO5 square pyramids that share corners with two equivalent Bi(3)O6 octahedra and edges with two equivalent Bi(4)O5 square pyramids. The corner-sharing octahedral tilt angles are 57°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Bi(3) and two equivalent Bi(4) atoms. In the second O site, O(2) is bonded to one Ca(1), one Bi(1), and two equivalent Bi(3) atoms to form distorted OCaBi3 trigonal pyramids that share corners with two equivalent O(2)CaBi3 trigonal pyramids and edges with two equivalent O(6)Ca2Bi3 square pyramids. In the third O site, O(3) is bonded in a trigonal planar geometry to one Bi(4) and two equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Bi(2) and two equivalent Bi(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Bi(1) atoms. In the sixth O site, O(6) is bonded to two equivalent Ca(1), one Bi(3), and two equivalent Bi(2) atoms to form distorted OCa2Bi3 square pyramids that share edges with two equivalent O(6)Ca2Bi3 square pyramids and edges with two equivalent O(2)CaBi3 trigonal pyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Bi(4) atoms. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Bi(2) and two equivalent Bi(3) atoms.
Ca(BiO2)4 crystallizes in the monoclinic Cm space group. Ca(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. The Ca(1)-O(2) bond length is 2.57 Å. Both Ca(1)-O(5) bond lengths are 2.44 Å. Both Ca(1)-O(6) bond lengths are 2.64 Å. Both Ca(1)-O(7) bond lengths are 2.50 Å. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted BiO5 square pyramids that share corners with two equivalent Bi(3)O6 octahedra and edges with two equivalent Bi(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 52°. The Bi(1)-O(2) bond length is 2.25 Å. Both Bi(1)-O(4) bond lengths are 2.31 Å. Both Bi(1)-O(5) bond lengths are 2.35 Å. In the second Bi site, Bi(2) is bonded in a 6-coordinate geometry to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms. The Bi(2)-O(4) bond length is 2.26 Å. The Bi(2)-O(8) bond length is 2.62 Å. Both Bi(2)-O(3) bond lengths are 2.28 Å. Both Bi(2)-O(6) bond lengths are 2.60 Å. In the third Bi site, Bi(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form BiO6 octahedra that share corners with two equivalent Bi(1)O5 square pyramids, corners with two equivalent Bi(4)O5 square pyramids, and edges with two equivalent Bi(3)O6 octahedra. The Bi(3)-O(1) bond length is 2.09 Å. The Bi(3)-O(6) bond length is 2.13 Å. Both Bi(3)-O(2) bond lengths are 2.22 Å. Both Bi(3)-O(8) bond lengths are 2.19 Å. In the fourth Bi site, Bi(4) is bonded to one O(3), two equivalent O(1), and two equivalent O(7) atoms to form BiO5 square pyramids that share corners with two equivalent Bi(3)O6 octahedra and edges with two equivalent Bi(4)O5 square pyramids. The corner-sharing octahedral tilt angles are 57°. The Bi(4)-O(3) bond length is 2.14 Å. Both Bi(4)-O(1) bond lengths are 2.40 Å. Both Bi(4)-O(7) bond lengths are 2.31 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Bi(3) and two equivalent Bi(4) atoms. In the second O site, O(2) is bonded to one Ca(1), one Bi(1), and two equivalent Bi(3) atoms to form distorted OCaBi3 trigonal pyramids that share corners with two equivalent O(2)CaBi3 trigonal pyramids and edges with two equivalent O(6)Ca2Bi3 square pyramids. In the third O site, O(3) is bonded in a trigonal planar geometry to one Bi(4) and two equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Bi(2) and two equivalent Bi(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Bi(1) atoms. In the sixth O site, O(6) is bonded to two equivalent Ca(1), one Bi(3), and two equivalent Bi(2) atoms to form distorted OCa2Bi3 square pyramids that share edges with two equivalent O(6)Ca2Bi3 square pyramids and edges with two equivalent O(2)CaBi3 trigonal pyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Bi(4) atoms. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Bi(2) and two equivalent Bi(3) atoms.