Ca2AlMnO5 crystallizes in the monoclinic Pm space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(13), one O(14), one O(15), one O(16), one O(3), one O(7), and one O(8) atom. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(13), one O(15), one O(16), one O(2), one O(4), one O(5), one O(6), and one O(7) atom. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(12), one O(13), one O(14), one O(15), and one O(9) atom. In the fourth Ca site, Ca(4) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(12), one O(15), one O(16), one O(2), one O(4), one O(5), and one O(9) atom. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(11), one O(2), one O(7), and two equivalent O(13) atoms to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Al(1)O4 tetrahedra, and corners with two equivalent Al(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-9°. In the second Mn site, Mn(2) is bonded to one O(1), one O(12), one O(2), one O(8), and two equivalent O(14) atoms to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Al(2)O4 tetrahedra, and corners with two equivalent Al(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-9°. In the third Mn site, Mn(3) is bonded to one O(3), one O(4), one O(9), and two equivalent O(15) atoms to form MnO5 trigonal bipyramids that share  a cornercorner with one Al(1)O4 tetrahedra, corners with two equivalent Mn(4)O5 trigonal bipyramids, and corners with two equivalent Al(3)O5 trigonal bipyramids. In the fourth Mn site, Mn(4) is bonded to one O(10), one O(3), one O(4), and two equivalent O(16) atoms to form distorted MnO5 trigonal bipyramids that share  a cornercorner with one Al(2)O4 tetrahedra, corners with two equivalent Mn(3)O5 trigonal bipyramids, and corners with two equivalent Al(4)O5 trigonal bipyramids. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(6), one O(9), and two equivalent O(13) atoms to form distorted AlO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra,  a cornercorner with one Al(2)O4 tetrahedra, and  a cornercorner with one Mn(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 36°. In the second Al site, Al(2) is bonded to one O(10), one O(6), and two equivalent O(14) atoms to form AlO4 tetrahedra that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra, and  a cornercorner with one Mn(4)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 37°. In the third Al site, Al(3) is bonded to one O(11), one O(5), one O(7), and two equivalent O(15) atoms to form AlO5 trigonal bipyramids that share corners with two equivalent Mn(1)O6 octahedra,  a cornercorner with one Al(4)O5 trigonal bipyramid, and corners with two equivalent Mn(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-7°. In the fourth Al site, Al(4) is bonded to one O(12), one O(5), one O(8), and two equivalent O(16) atoms to form AlO5 trigonal bipyramids that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid, and corners with two equivalent Mn(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 14-23°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1), two equivalent Ca(3), one Mn(1), and one Mn(2) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(2)Ca4Mn2 octahedra, corners with two equivalent O(3)Ca2Mn2 tetrahedra,  a faceface with one O(11)Ca4MnAl octahedra,  a faceface with one O(12)Ca4MnAl octahedra, and  a faceface with one O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 2-7°. In the second O site, O(2) is bonded to two equivalent Ca(2), two equivalent Ca(4), one Mn(1), and one Mn(2) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(1)Ca4Mn2 octahedra, corners with two equivalent O(6)Ca2Al2 tetrahedra, edges with two equivalent O(5)Ca4Al2 octahedra,  a faceface with one O(11)Ca4MnAl octahedra,  a faceface with one O(12)Ca4MnAl octahedra, and  a faceface with one O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 2-7°. In the third O site, O(3) is bonded to two equivalent Ca(1), one Mn(3), and one Mn(4) atom to form distorted OCa2Mn2 tetrahedra that share corners with two equivalent O(1)Ca4Mn2 octahedra and corners with two equivalent O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 19-51°. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Ca(2), two equivalent Ca(4), one Mn(3), and one Mn(4) atom. In the fifth O site, O(5) is bonded to two equivalent Ca(2), two equivalent Ca(4), one Al(3), and one Al(4) atom to form distorted OCa4Al2 octahedra that share corners with two equivalent O(6)Ca2Al2 tetrahedra, edges with two equivalent O(2)Ca4Mn2 octahedra,  a faceface with one O(11)Ca4MnAl octahedra,  a faceface with one O(12)Ca4MnAl octahedra, and  a faceface with one O(7)Ca4MnAl octahedra. In the sixth O site, O(6) is bonded to two equivalent Ca(2), one Al(1), and one Al(2) atom to form distorted OCa2Al2 tetrahedra that share corners with two equivalent O(5)Ca4Al2 octahedra, corners with two equivalent O(2)Ca4Mn2 octahedra, and corners with two equivalent O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 11-83°. In the seventh O site, O(7) is bonded to two equivalent Ca(1), two equivalent Ca(2), one Mn(1), and one Al(3) atom to form distorted OCa4MnAl octahedra that share corners with two equivalent O(11)Ca4MnAl octahedra, corners with two equivalent O(6)Ca2Al2 tetrahedra, corners with two equivalent O(3)Ca2Mn2 tetrahedra,  a faceface with one O(5)Ca4Al2 octahedra,  a faceface with one O(1)Ca4Mn2 octahedra, and  a faceface with one O(2)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca(1), one Mn(2), and one Al(4) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to two equivalent Ca(3), two equivalent Ca(4), one Mn(3), and one Al(1) atom. In the tenth O site, O(10) is bonded in a distorted see-saw-like geometry to two equivalent Ca(4), one Mn(4), and one Al(2) atom. In the eleventh O site, O(11) is bonded to two equivalent Ca(3), two equivalent Ca(4), one Mn(1), and one Al(3) atom to form distorted OCa4MnAl octahedra that share corners with two equivalent O(7)Ca4MnAl octahedra, edges with two equivalent O(12)Ca4MnAl octahedra,  a faceface with one O(5)Ca4Al2 octahedra,  a faceface with one O(1)Ca4Mn2 octahedra, and  a faceface with one O(2)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the twelfth O site, O(12) is bonded to two equivalent Ca(3), two equivalent Ca(4), one Mn(2), and one Al(4) atom to form distorted OCa4MnAl octahedra that share edges with two equivalent O(11)Ca4MnAl octahedra,  a faceface with one O(5)Ca4Al2 octahedra,  a faceface with one O(1)Ca4Mn2 octahedra, and  a faceface with one O(2)Ca4Mn2 octahedra. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Mn(1), and one Al(1) atom. In the fourteenth O site, O(14) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Ca(3), one Mn(2), and one Al(2) atom. In the fifteenth O site, O(15) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Ca(4), one Mn(3), and one Al(3) atom. In the sixteenth O site, O(16) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), one Mn(4), and one Al(4) atom.
Ca2AlMnO5 crystallizes in the monoclinic Pm space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(13), one O(14), one O(15), one O(16), one O(3), one O(7), and one O(8) atom. The Ca(1)-O(1) bond length is 2.66 Å. The Ca(1)-O(13) bond length is 2.32 Å. The Ca(1)-O(14) bond length is 2.36 Å. The Ca(1)-O(15) bond length is 2.51 Å. The Ca(1)-O(16) bond length is 2.78 Å. The Ca(1)-O(3) bond length is 2.34 Å. The Ca(1)-O(7) bond length is 2.61 Å. The Ca(1)-O(8) bond length is 2.35 Å. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(13), one O(15), one O(16), one O(2), one O(4), one O(5), one O(6), and one O(7) atom. The Ca(2)-O(13) bond length is 2.50 Å. The Ca(2)-O(15) bond length is 2.96 Å. The Ca(2)-O(16) bond length is 2.61 Å. The Ca(2)-O(2) bond length is 2.66 Å. The Ca(2)-O(4) bond length is 2.40 Å. The Ca(2)-O(5) bond length is 2.64 Å. The Ca(2)-O(6) bond length is 2.43 Å. The Ca(2)-O(7) bond length is 2.58 Å. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(12), one O(13), one O(14), one O(15), and one O(9) atom. The Ca(3)-O(1) bond length is 2.35 Å. The Ca(3)-O(11) bond length is 2.53 Å. The Ca(3)-O(12) bond length is 2.64 Å. The Ca(3)-O(13) bond length is 2.60 Å. The Ca(3)-O(14) bond length is 2.41 Å. The Ca(3)-O(15) bond length is 2.50 Å. The Ca(3)-O(9) bond length is 2.48 Å. In the fourth Ca site, Ca(4) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(12), one O(15), one O(16), one O(2), one O(4), one O(5), and one O(9) atom. The Ca(4)-O(10) bond length is 2.33 Å. The Ca(4)-O(11) bond length is 2.60 Å. The Ca(4)-O(12) bond length is 2.70 Å. The Ca(4)-O(15) bond length is 2.91 Å. The Ca(4)-O(16) bond length is 2.46 Å. The Ca(4)-O(2) bond length is 2.83 Å. The Ca(4)-O(4) bond length is 3.02 Å. The Ca(4)-O(5) bond length is 2.44 Å. The Ca(4)-O(9) bond length is 3.08 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(11), one O(2), one O(7), and two equivalent O(13) atoms to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Al(1)O4 tetrahedra, and corners with two equivalent Al(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-9°. The Mn(1)-O(1) bond length is 1.92 Å. The Mn(1)-O(11) bond length is 1.98 Å. The Mn(1)-O(2) bond length is 1.96 Å. The Mn(1)-O(7) bond length is 1.91 Å. Both Mn(1)-O(13) bond lengths are 2.24 Å. In the second Mn site, Mn(2) is bonded to one O(1), one O(12), one O(2), one O(8), and two equivalent O(14) atoms to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Al(2)O4 tetrahedra, and corners with two equivalent Al(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-9°. The Mn(2)-O(1) bond length is 1.89 Å. The Mn(2)-O(12) bond length is 2.10 Å. The Mn(2)-O(2) bond length is 1.91 Å. The Mn(2)-O(8) bond length is 2.04 Å. Both Mn(2)-O(14) bond lengths are 2.28 Å. In the third Mn site, Mn(3) is bonded to one O(3), one O(4), one O(9), and two equivalent O(15) atoms to form MnO5 trigonal bipyramids that share  a cornercorner with one Al(1)O4 tetrahedra, corners with two equivalent Mn(4)O5 trigonal bipyramids, and corners with two equivalent Al(3)O5 trigonal bipyramids. The Mn(3)-O(3) bond length is 1.97 Å. The Mn(3)-O(4) bond length is 1.92 Å. The Mn(3)-O(9) bond length is 2.08 Å. Both Mn(3)-O(15) bond lengths are 2.02 Å. In the fourth Mn site, Mn(4) is bonded to one O(10), one O(3), one O(4), and two equivalent O(16) atoms to form distorted MnO5 trigonal bipyramids that share  a cornercorner with one Al(2)O4 tetrahedra, corners with two equivalent Mn(3)O5 trigonal bipyramids, and corners with two equivalent Al(4)O5 trigonal bipyramids. The Mn(4)-O(10) bond length is 1.99 Å. The Mn(4)-O(3) bond length is 1.96 Å. The Mn(4)-O(4) bond length is 2.29 Å. Both Mn(4)-O(16) bond lengths are 1.89 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(6), one O(9), and two equivalent O(13) atoms to form distorted AlO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra,  a cornercorner with one Al(2)O4 tetrahedra, and  a cornercorner with one Mn(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 36°. The Al(1)-O(6) bond length is 1.79 Å. The Al(1)-O(9) bond length is 1.77 Å. Both Al(1)-O(13) bond lengths are 1.75 Å. In the second Al site, Al(2) is bonded to one O(10), one O(6), and two equivalent O(14) atoms to form AlO4 tetrahedra that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra, and  a cornercorner with one Mn(4)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 37°. The Al(2)-O(10) bond length is 1.77 Å. The Al(2)-O(6) bond length is 1.76 Å. Both Al(2)-O(14) bond lengths are 1.75 Å. In the third Al site, Al(3) is bonded to one O(11), one O(5), one O(7), and two equivalent O(15) atoms to form AlO5 trigonal bipyramids that share corners with two equivalent Mn(1)O6 octahedra,  a cornercorner with one Al(4)O5 trigonal bipyramid, and corners with two equivalent Mn(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-7°. The Al(3)-O(11) bond length is 1.95 Å. The Al(3)-O(5) bond length is 1.78 Å. The Al(3)-O(7) bond length is 1.85 Å. Both Al(3)-O(15) bond lengths are 1.85 Å. In the fourth Al site, Al(4) is bonded to one O(12), one O(5), one O(8), and two equivalent O(16) atoms to form AlO5 trigonal bipyramids that share corners with two equivalent Mn(2)O6 octahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid, and corners with two equivalent Mn(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 14-23°. The Al(4)-O(12) bond length is 1.86 Å. The Al(4)-O(5) bond length is 1.80 Å. The Al(4)-O(8) bond length is 1.82 Å. Both Al(4)-O(16) bond lengths are 1.90 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1), two equivalent Ca(3), one Mn(1), and one Mn(2) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(2)Ca4Mn2 octahedra, corners with two equivalent O(3)Ca2Mn2 tetrahedra,  a faceface with one O(11)Ca4MnAl octahedra,  a faceface with one O(12)Ca4MnAl octahedra, and  a faceface with one O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 2-7°. In the second O site, O(2) is bonded to two equivalent Ca(2), two equivalent Ca(4), one Mn(1), and one Mn(2) atom to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(1)Ca4Mn2 octahedra, corners with two equivalent O(6)Ca2Al2 tetrahedra, edges with two equivalent O(5)Ca4Al2 octahedra,  a faceface with one O(11)Ca4MnAl octahedra,  a faceface with one O(12)Ca4MnAl octahedra, and  a faceface with one O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 2-7°. In the third O site, O(3) is bonded to two equivalent Ca(1), one Mn(3), and one Mn(4) atom to form distorted OCa2Mn2 tetrahedra that share corners with two equivalent O(1)Ca4Mn2 octahedra and corners with two equivalent O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 19-51°. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Ca(2), two equivalent Ca(4), one Mn(3), and one Mn(4) atom. In the fifth O site, O(5) is bonded to two equivalent Ca(2), two equivalent Ca(4), one Al(3), and one Al(4) atom to form distorted OCa4Al2 octahedra that share corners with two equivalent O(6)Ca2Al2 tetrahedra, edges with two equivalent O(2)Ca4Mn2 octahedra,  a faceface with one O(11)Ca4MnAl octahedra,  a faceface with one O(12)Ca4MnAl octahedra, and  a faceface with one O(7)Ca4MnAl octahedra. In the sixth O site, O(6) is bonded to two equivalent Ca(2), one Al(1), and one Al(2) atom to form distorted OCa2Al2 tetrahedra that share corners with two equivalent O(5)Ca4Al2 octahedra, corners with two equivalent O(2)Ca4Mn2 octahedra, and corners with two equivalent O(7)Ca4MnAl octahedra. The corner-sharing octahedral tilt angles range from 11-83°. In the seventh O site, O(7) is bonded to two equivalent Ca(1), two equivalent Ca(2), one Mn(1), and one Al(3) atom to form distorted OCa4MnAl octahedra that share corners with two equivalent O(11)Ca4MnAl octahedra, corners with two equivalent O(6)Ca2Al2 tetrahedra, corners with two equivalent O(3)Ca2Mn2 tetrahedra,  a faceface with one O(5)Ca4Al2 octahedra,  a faceface with one O(1)Ca4Mn2 octahedra, and  a faceface with one O(2)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca(1), one Mn(2), and one Al(4) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to two equivalent Ca(3), two equivalent Ca(4), one Mn(3), and one Al(1) atom. In the tenth O site, O(10) is bonded in a distorted see-saw-like geometry to two equivalent Ca(4), one Mn(4), and one Al(2) atom. In the eleventh O site, O(11) is bonded to two equivalent Ca(3), two equivalent Ca(4), one Mn(1), and one Al(3) atom to form distorted OCa4MnAl octahedra that share corners with two equivalent O(7)Ca4MnAl octahedra, edges with two equivalent O(12)Ca4MnAl octahedra,  a faceface with one O(5)Ca4Al2 octahedra,  a faceface with one O(1)Ca4Mn2 octahedra, and  a faceface with one O(2)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the twelfth O site, O(12) is bonded to two equivalent Ca(3), two equivalent Ca(4), one Mn(2), and one Al(4) atom to form distorted OCa4MnAl octahedra that share edges with two equivalent O(11)Ca4MnAl octahedra,  a faceface with one O(5)Ca4Al2 octahedra,  a faceface with one O(1)Ca4Mn2 octahedra, and  a faceface with one O(2)Ca4Mn2 octahedra. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Mn(1), and one Al(1) atom. In the fourteenth O site, O(14) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Ca(3), one Mn(2), and one Al(2) atom. In the fifteenth O site, O(15) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Ca(4), one Mn(3), and one Al(3) atom. In the sixteenth O site, O(16) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), one Mn(4), and one Al(4) atom.