Ca2Mn2O5 crystallizes in the monoclinic Cm space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to two equivalent O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(2), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to one O(11), one O(3), one O(4), one O(6), one O(8), and one O(9) atom. In the fifth Ca site, Ca(5) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(11), two equivalent O(2), and two equivalent O(9) atoms. In the sixth Ca site, Ca(6) is bonded in a 10-coordinate geometry to one O(1), one O(4), two equivalent O(10), two equivalent O(11), two equivalent O(3), and two equivalent O(9) atoms. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted trigonal planar geometry to one O(1) and two equivalent O(5) atoms. In the second Mn site, Mn(2) is bonded to one O(1), two equivalent O(6), and two equivalent O(9) atoms to form corner-sharing MnO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 4-11°. In the third Mn site, Mn(3) is bonded to one O(10), one O(2), one O(3), one O(5), and one O(7) atom to form MnO5 trigonal bipyramids that share corners with two equivalent Mn(4)O6 octahedra and corners with two equivalent Mn(5)O5 square pyramids. The corner-sharing octahedral tilt angles range from 14-38°. In the fourth Mn site, Mn(4) is bonded to one O(11), one O(2), one O(3), one O(6), one O(8), and one O(9) atom to form corner-sharing MnO6 octahedra. In the fifth Mn site, Mn(5) is bonded to one O(4), two equivalent O(10), and two equivalent O(7) atoms to form corner-sharing MnO5 square pyramids. In the sixth Mn site, Mn(6) is bonded to one O(4), two equivalent O(11), and two equivalent O(8) atoms to form MnO5 square pyramids that share corners with four equivalent Mn(4)O6 octahedra and  a cornercorner with one Mn(5)O5 square pyramid. The corner-sharing octahedral tilt angles range from 3-13°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(6), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded to one Ca(3), one Ca(5), one Mn(3), and one Mn(4) atom to form distorted OCa2Mn2 tetrahedra that share corners with two equivalent O(11)Ca4Mn2 octahedra,  a cornercorner with one O(2)Ca2Mn2 tetrahedra, corners with two equivalent O(5)Ca2Mn2 tetrahedra,  an edgeedge with one O(11)Ca4Mn2 octahedra, and  an edgeedge with one O(8)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles are 44°. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(2), one Ca(4), one Ca(6), one Mn(3), and one Mn(4) atom. In the fourth O site, O(4) is bonded to one Ca(2), one Ca(6), two equivalent Ca(4), one Mn(5), and one Mn(6) atom to form distorted face-sharing OCa4Mn2 octahedra. In the fifth O site, O(5) is bonded to one Ca(1), one Ca(3), one Mn(1), and one Mn(3) atom to form distorted OCa2Mn2 tetrahedra that share  a cornercorner with one O(11)Ca4Mn2 octahedra, corners with three equivalent O(8)Ca4Mn2 octahedra, corners with two equivalent O(2)Ca2Mn2 tetrahedra, and  an edgeedge with one O(5)Ca2Mn2 tetrahedra. The corner-sharing octahedral tilt angles range from 10-68°. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Ca(4), one Mn(2), and one Mn(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Mn(3), and one Mn(5) atom. In the eighth O site, O(8) is bonded to one Ca(1), one Ca(2), one Ca(3), one Ca(4), one Mn(4), and one Mn(6) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(11)Ca4Mn2 octahedra, corners with three equivalent O(5)Ca2Mn2 tetrahedra,  an edgeedge with one O(2)Ca2Mn2 tetrahedra,  a faceface with one O(11)Ca4Mn2 octahedra,  a faceface with one O(4)Ca4Mn2 octahedra, and  a faceface with one O(8)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to one Ca(3), one Ca(4), one Ca(5), one Ca(6), one Mn(2), and one Mn(4) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Ca(3), one Ca(5), one Ca(6), one Mn(3), and one Mn(5) atom. In the eleventh O site, O(11) is bonded to one Ca(3), one Ca(4), one Ca(5), one Ca(6), one Mn(4), and one Mn(6) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(8)Ca4Mn2 octahedra,  a cornercorner with one O(5)Ca2Mn2 tetrahedra, corners with two equivalent O(2)Ca2Mn2 tetrahedra,  an edgeedge with one O(2)Ca2Mn2 tetrahedra,  a faceface with one O(11)Ca4Mn2 octahedra,  a faceface with one O(4)Ca4Mn2 octahedra, and  a faceface with one O(8)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 7-8°.
Ca2Mn2O5 crystallizes in the monoclinic Cm space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to two equivalent O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms. Both Ca(1)-O(5) bond lengths are 2.48 Å. Both Ca(1)-O(6) bond lengths are 2.75 Å. Both Ca(1)-O(7) bond lengths are 2.47 Å. Both Ca(1)-O(8) bond lengths are 2.60 Å. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms. The Ca(2)-O(4) bond length is 2.46 Å. Both Ca(2)-O(3) bond lengths are 2.73 Å. Both Ca(2)-O(6) bond lengths are 2.47 Å. Both Ca(2)-O(8) bond lengths are 2.44 Å. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(2), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. The Ca(3)-O(10) bond length is 2.73 Å. The Ca(3)-O(11) bond length is 2.72 Å. The Ca(3)-O(2) bond length is 2.40 Å. The Ca(3)-O(5) bond length is 2.32 Å. The Ca(3)-O(6) bond length is 3.02 Å. The Ca(3)-O(7) bond length is 2.47 Å. The Ca(3)-O(8) bond length is 2.37 Å. The Ca(3)-O(9) bond length is 2.56 Å. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to one O(11), one O(3), one O(4), one O(6), one O(8), and one O(9) atom. The Ca(4)-O(11) bond length is 2.50 Å. The Ca(4)-O(3) bond length is 2.42 Å. The Ca(4)-O(4) bond length is 2.66 Å. The Ca(4)-O(6) bond length is 2.61 Å. The Ca(4)-O(8) bond length is 2.59 Å. The Ca(4)-O(9) bond length is 2.48 Å. In the fifth Ca site, Ca(5) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(11), two equivalent O(2), and two equivalent O(9) atoms. Both Ca(5)-O(10) bond lengths are 2.79 Å. Both Ca(5)-O(11) bond lengths are 2.47 Å. Both Ca(5)-O(2) bond lengths are 2.34 Å. Both Ca(5)-O(9) bond lengths are 2.80 Å. In the sixth Ca site, Ca(6) is bonded in a 10-coordinate geometry to one O(1), one O(4), two equivalent O(10), two equivalent O(11), two equivalent O(3), and two equivalent O(9) atoms. The Ca(6)-O(1) bond length is 2.34 Å. The Ca(6)-O(4) bond length is 2.69 Å. Both Ca(6)-O(10) bond lengths are 2.60 Å. Both Ca(6)-O(11) bond lengths are 2.68 Å. Both Ca(6)-O(3) bond lengths are 2.92 Å. Both Ca(6)-O(9) bond lengths are 2.92 Å. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted trigonal planar geometry to one O(1) and two equivalent O(5) atoms. The Mn(1)-O(1) bond length is 1.84 Å. Both Mn(1)-O(5) bond lengths are 1.85 Å. In the second Mn site, Mn(2) is bonded to one O(1), two equivalent O(6), and two equivalent O(9) atoms to form corner-sharing MnO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 4-11°. The Mn(2)-O(1) bond length is 2.20 Å. Both Mn(2)-O(6) bond lengths are 1.98 Å. Both Mn(2)-O(9) bond lengths are 1.93 Å. In the third Mn site, Mn(3) is bonded to one O(10), one O(2), one O(3), one O(5), and one O(7) atom to form MnO5 trigonal bipyramids that share corners with two equivalent Mn(4)O6 octahedra and corners with two equivalent Mn(5)O5 square pyramids. The corner-sharing octahedral tilt angles range from 14-38°. The Mn(3)-O(10) bond length is 1.99 Å. The Mn(3)-O(2) bond length is 1.90 Å. The Mn(3)-O(3) bond length is 1.94 Å. The Mn(3)-O(5) bond length is 2.10 Å. The Mn(3)-O(7) bond length is 2.02 Å. In the fourth Mn site, Mn(4) is bonded to one O(11), one O(2), one O(3), one O(6), one O(8), and one O(9) atom to form corner-sharing MnO6 octahedra. The Mn(4)-O(11) bond length is 2.01 Å. The Mn(4)-O(2) bond length is 2.04 Å. The Mn(4)-O(3) bond length is 2.03 Å. The Mn(4)-O(6) bond length is 2.01 Å. The Mn(4)-O(8) bond length is 2.06 Å. The Mn(4)-O(9) bond length is 1.99 Å. In the fifth Mn site, Mn(5) is bonded to one O(4), two equivalent O(10), and two equivalent O(7) atoms to form corner-sharing MnO5 square pyramids. The Mn(5)-O(4) bond length is 1.93 Å. Both Mn(5)-O(10) bond lengths are 1.97 Å. Both Mn(5)-O(7) bond lengths are 1.95 Å. In the sixth Mn site, Mn(6) is bonded to one O(4), two equivalent O(11), and two equivalent O(8) atoms to form MnO5 square pyramids that share corners with four equivalent Mn(4)O6 octahedra and  a cornercorner with one Mn(5)O5 square pyramid. The corner-sharing octahedral tilt angles range from 3-13°. The Mn(6)-O(4) bond length is 1.94 Å. Both Mn(6)-O(11) bond lengths are 1.91 Å. Both Mn(6)-O(8) bond lengths are 1.92 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(6), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded to one Ca(3), one Ca(5), one Mn(3), and one Mn(4) atom to form distorted OCa2Mn2 tetrahedra that share corners with two equivalent O(11)Ca4Mn2 octahedra,  a cornercorner with one O(2)Ca2Mn2 tetrahedra, corners with two equivalent O(5)Ca2Mn2 tetrahedra,  an edgeedge with one O(11)Ca4Mn2 octahedra, and  an edgeedge with one O(8)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles are 44°. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(2), one Ca(4), one Ca(6), one Mn(3), and one Mn(4) atom. In the fourth O site, O(4) is bonded to one Ca(2), one Ca(6), two equivalent Ca(4), one Mn(5), and one Mn(6) atom to form distorted face-sharing OCa4Mn2 octahedra. In the fifth O site, O(5) is bonded to one Ca(1), one Ca(3), one Mn(1), and one Mn(3) atom to form distorted OCa2Mn2 tetrahedra that share  a cornercorner with one O(11)Ca4Mn2 octahedra, corners with three equivalent O(8)Ca4Mn2 octahedra, corners with two equivalent O(2)Ca2Mn2 tetrahedra, and  an edgeedge with one O(5)Ca2Mn2 tetrahedra. The corner-sharing octahedral tilt angles range from 10-68°. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Ca(4), one Mn(2), and one Mn(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Mn(3), and one Mn(5) atom. In the eighth O site, O(8) is bonded to one Ca(1), one Ca(2), one Ca(3), one Ca(4), one Mn(4), and one Mn(6) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(11)Ca4Mn2 octahedra, corners with three equivalent O(5)Ca2Mn2 tetrahedra,  an edgeedge with one O(2)Ca2Mn2 tetrahedra,  a faceface with one O(11)Ca4Mn2 octahedra,  a faceface with one O(4)Ca4Mn2 octahedra, and  a faceface with one O(8)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to one Ca(3), one Ca(4), one Ca(5), one Ca(6), one Mn(2), and one Mn(4) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Ca(3), one Ca(5), one Ca(6), one Mn(3), and one Mn(5) atom. In the eleventh O site, O(11) is bonded to one Ca(3), one Ca(4), one Ca(5), one Ca(6), one Mn(4), and one Mn(6) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(8)Ca4Mn2 octahedra,  a cornercorner with one O(5)Ca2Mn2 tetrahedra, corners with two equivalent O(2)Ca2Mn2 tetrahedra,  an edgeedge with one O(2)Ca2Mn2 tetrahedra,  a faceface with one O(11)Ca4Mn2 octahedra,  a faceface with one O(4)Ca4Mn2 octahedra, and  a faceface with one O(8)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 7-8°.