CaMnBiO5 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with four equivalent Mn(1)O4 tetrahedra and  an edgeedge with one Ca(1)O6 octahedra. Mn(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form MnO4 tetrahedra that share corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-51°. Bi(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form edge-sharing OCa2Bi2 tetrahedra. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom.
CaMnBiO5 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with four equivalent Mn(1)O4 tetrahedra and  an edgeedge with one Ca(1)O6 octahedra. The Ca(1)-O(1) bond length is 2.40 Å. The Ca(1)-O(2) bond length is 2.38 Å. The Ca(1)-O(3) bond length is 2.31 Å. The Ca(1)-O(5) bond length is 2.34 Å. There is one shorter (2.37 Å) and one longer (2.44 Å) Ca(1)-O(4) bond length. Mn(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form MnO4 tetrahedra that share corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-51°. The Mn(1)-O(1) bond length is 1.71 Å. The Mn(1)-O(2) bond length is 1.72 Å. The Mn(1)-O(3) bond length is 1.71 Å. The Mn(1)-O(5) bond length is 1.73 Å. Bi(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms. The Bi(1)-O(1) bond length is 2.41 Å. The Bi(1)-O(2) bond length is 2.45 Å. The Bi(1)-O(3) bond length is 2.66 Å. The Bi(1)-O(5) bond length is 2.41 Å. There is one shorter (2.16 Å) and one longer (2.30 Å) Bi(1)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form edge-sharing OCa2Bi2 tetrahedra. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Bi(1) atom.