Ca3Fe2(ReO6)2 crystallizes in the triclinic P1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(3), one O(4), one O(5), one O(7), one O(8), and one O(9) atom. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(3), one O(4), one O(6), one O(7), one O(8), and one O(9) atom. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), one O(6), one O(8), and one O(9) atom. There are two inequivalent Re sites. In the first Re site, Re(1) is bonded to one O(12), one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form ReO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 22-31°. In the second Re site, Re(2) is bonded to one O(1), one O(10), one O(11), one O(3), one O(6), and one O(8) atom to form ReO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 23-32°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(12), one O(3), one O(5), one O(7), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent Re(2)O6 octahedra and corners with four equivalent Re(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 22-31°. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(2), one O(4), one O(6), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Re(1)O6 octahedra and corners with four equivalent Re(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 23-32°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(3), one Re(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(3), one Re(1), and one Fe(2) atom. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), one Re(2), and one Fe(1) atom to form distorted OCa2FeRe tetrahedra that share corners with two equivalent O(4)Ca2FeRe tetrahedra,  a cornercorner with one O(8)Ca3FeRe trigonal bipyramid, corners with three equivalent O(10)Ca2FeRe trigonal pyramids, corners with three equivalent O(7)Ca2FeRe trigonal pyramids,  an edgeedge with one O(8)Ca3FeRe trigonal bipyramid, and  an edgeedge with one O(12)Ca2FeRe trigonal pyramid. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), one Re(1), and one Fe(2) atom to form distorted OCa2FeRe tetrahedra that share corners with two equivalent O(3)Ca2FeRe tetrahedra, corners with three equivalent O(8)Ca3FeRe trigonal bipyramids,  a cornercorner with one O(10)Ca2FeRe trigonal pyramid,  a cornercorner with one O(7)Ca2FeRe trigonal pyramid,  an edgeedge with one O(10)Ca2FeRe trigonal pyramid,  an edgeedge with one O(12)Ca2FeRe trigonal pyramid, and  an edgeedge with one O(7)Ca2FeRe trigonal pyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Re(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Re(2), and one Fe(2) atom. In the seventh O site, O(7) is bonded to one Ca(1), one Ca(2), one Re(1), and one Fe(1) atom to form distorted OCa2FeRe trigonal pyramids that share  a cornercorner with one O(4)Ca2FeRe tetrahedra, corners with three equivalent O(3)Ca2FeRe tetrahedra, corners with two equivalent O(8)Ca3FeRe trigonal bipyramids,  a cornercorner with one O(12)Ca2FeRe trigonal pyramid,  an edgeedge with one O(4)Ca2FeRe tetrahedra,  an edgeedge with one O(10)Ca2FeRe trigonal pyramid, and  an edgeedge with one O(12)Ca2FeRe trigonal pyramid. In the eighth O site, O(8) is bonded to one Ca(1), one Ca(2), one Ca(3), one Re(2), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing OCa3FeRe trigonal bipyramids. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Re(1), and one Fe(1) atom. In the tenth O site, O(10) is bonded to one Ca(1), one Ca(2), one Re(2), and one Fe(2) atom to form distorted OCa2FeRe trigonal pyramids that share  a cornercorner with one O(4)Ca2FeRe tetrahedra, corners with three equivalent O(3)Ca2FeRe tetrahedra,  a cornercorner with one O(12)Ca2FeRe trigonal pyramid,  an edgeedge with one O(4)Ca2FeRe tetrahedra, edges with two equivalent O(8)Ca3FeRe trigonal bipyramids, and  an edgeedge with one O(7)Ca2FeRe trigonal pyramid. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Re(2), and one Fe(2) atom. In the twelfth O site, O(12) is bonded to one Ca(2), one Ca(3), one Re(1), and one Fe(1) atom to form distorted OCa2FeRe trigonal pyramids that share corners with two equivalent O(8)Ca3FeRe trigonal bipyramids,  a cornercorner with one O(10)Ca2FeRe trigonal pyramid,  a cornercorner with one O(7)Ca2FeRe trigonal pyramid,  an edgeedge with one O(3)Ca2FeRe tetrahedra,  an edgeedge with one O(4)Ca2FeRe tetrahedra, and  an edgeedge with one O(7)Ca2FeRe trigonal pyramid.
Ca3Fe2(ReO6)2 crystallizes in the triclinic P1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(3), one O(4), one O(5), one O(7), one O(8), and one O(9) atom. The Ca(1)-O(10) bond length is 2.39 Å. The Ca(1)-O(11) bond length is 2.72 Å. The Ca(1)-O(3) bond length is 2.39 Å. The Ca(1)-O(4) bond length is 2.33 Å. The Ca(1)-O(5) bond length is 2.66 Å. The Ca(1)-O(7) bond length is 2.37 Å. The Ca(1)-O(8) bond length is 2.59 Å. The Ca(1)-O(9) bond length is 2.53 Å. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(3), one O(4), one O(6), one O(7), one O(8), and one O(9) atom. The Ca(2)-O(10) bond length is 2.53 Å. The Ca(2)-O(12) bond length is 2.61 Å. The Ca(2)-O(3) bond length is 2.35 Å. The Ca(2)-O(4) bond length is 2.42 Å. The Ca(2)-O(6) bond length is 2.60 Å. The Ca(2)-O(7) bond length is 2.53 Å. The Ca(2)-O(8) bond length is 2.38 Å. The Ca(2)-O(9) bond length is 2.39 Å. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), one O(6), one O(8), and one O(9) atom. The Ca(3)-O(1) bond length is 2.35 Å. The Ca(3)-O(11) bond length is 2.54 Å. The Ca(3)-O(12) bond length is 2.38 Å. The Ca(3)-O(2) bond length is 2.43 Å. The Ca(3)-O(5) bond length is 2.59 Å. The Ca(3)-O(6) bond length is 2.37 Å. The Ca(3)-O(8) bond length is 2.64 Å. The Ca(3)-O(9) bond length is 2.70 Å. There are two inequivalent Re sites. In the first Re site, Re(1) is bonded to one O(12), one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form ReO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 22-31°. The Re(1)-O(12) bond length is 1.92 Å. The Re(1)-O(2) bond length is 1.85 Å. The Re(1)-O(4) bond length is 2.01 Å. The Re(1)-O(5) bond length is 1.88 Å. The Re(1)-O(7) bond length is 1.94 Å. The Re(1)-O(9) bond length is 1.97 Å. In the second Re site, Re(2) is bonded to one O(1), one O(10), one O(11), one O(3), one O(6), and one O(8) atom to form ReO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 23-32°. The Re(2)-O(1) bond length is 1.87 Å. The Re(2)-O(10) bond length is 1.92 Å. The Re(2)-O(11) bond length is 1.91 Å. The Re(2)-O(3) bond length is 2.00 Å. The Re(2)-O(6) bond length is 1.91 Å. The Re(2)-O(8) bond length is 1.97 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(12), one O(3), one O(5), one O(7), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent Re(2)O6 octahedra and corners with four equivalent Re(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 22-31°. The Fe(1)-O(1) bond length is 2.01 Å. The Fe(1)-O(12) bond length is 2.02 Å. The Fe(1)-O(3) bond length is 2.06 Å. The Fe(1)-O(5) bond length is 2.07 Å. The Fe(1)-O(7) bond length is 2.02 Å. The Fe(1)-O(9) bond length is 2.09 Å. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(2), one O(4), one O(6), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Re(1)O6 octahedra and corners with four equivalent Re(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 23-32°. The Fe(2)-O(10) bond length is 2.07 Å. The Fe(2)-O(11) bond length is 2.03 Å. The Fe(2)-O(2) bond length is 2.01 Å. The Fe(2)-O(4) bond length is 2.06 Å. The Fe(2)-O(6) bond length is 2.02 Å. The Fe(2)-O(8) bond length is 2.07 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(3), one Re(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(3), one Re(1), and one Fe(2) atom. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), one Re(2), and one Fe(1) atom to form distorted OCa2FeRe tetrahedra that share corners with two equivalent O(4)Ca2FeRe tetrahedra,  a cornercorner with one O(8)Ca3FeRe trigonal bipyramid, corners with three equivalent O(10)Ca2FeRe trigonal pyramids, corners with three equivalent O(7)Ca2FeRe trigonal pyramids,  an edgeedge with one O(8)Ca3FeRe trigonal bipyramid, and  an edgeedge with one O(12)Ca2FeRe trigonal pyramid. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), one Re(1), and one Fe(2) atom to form distorted OCa2FeRe tetrahedra that share corners with two equivalent O(3)Ca2FeRe tetrahedra, corners with three equivalent O(8)Ca3FeRe trigonal bipyramids,  a cornercorner with one O(10)Ca2FeRe trigonal pyramid,  a cornercorner with one O(7)Ca2FeRe trigonal pyramid,  an edgeedge with one O(10)Ca2FeRe trigonal pyramid,  an edgeedge with one O(12)Ca2FeRe trigonal pyramid, and  an edgeedge with one O(7)Ca2FeRe trigonal pyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Re(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Re(2), and one Fe(2) atom. In the seventh O site, O(7) is bonded to one Ca(1), one Ca(2), one Re(1), and one Fe(1) atom to form distorted OCa2FeRe trigonal pyramids that share  a cornercorner with one O(4)Ca2FeRe tetrahedra, corners with three equivalent O(3)Ca2FeRe tetrahedra, corners with two equivalent O(8)Ca3FeRe trigonal bipyramids,  a cornercorner with one O(12)Ca2FeRe trigonal pyramid,  an edgeedge with one O(4)Ca2FeRe tetrahedra,  an edgeedge with one O(10)Ca2FeRe trigonal pyramid, and  an edgeedge with one O(12)Ca2FeRe trigonal pyramid. In the eighth O site, O(8) is bonded to one Ca(1), one Ca(2), one Ca(3), one Re(2), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing OCa3FeRe trigonal bipyramids. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Re(1), and one Fe(1) atom. In the tenth O site, O(10) is bonded to one Ca(1), one Ca(2), one Re(2), and one Fe(2) atom to form distorted OCa2FeRe trigonal pyramids that share  a cornercorner with one O(4)Ca2FeRe tetrahedra, corners with three equivalent O(3)Ca2FeRe tetrahedra,  a cornercorner with one O(12)Ca2FeRe trigonal pyramid,  an edgeedge with one O(4)Ca2FeRe tetrahedra, edges with two equivalent O(8)Ca3FeRe trigonal bipyramids, and  an edgeedge with one O(7)Ca2FeRe trigonal pyramid. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Re(2), and one Fe(2) atom. In the twelfth O site, O(12) is bonded to one Ca(2), one Ca(3), one Re(1), and one Fe(1) atom to form distorted OCa2FeRe trigonal pyramids that share corners with two equivalent O(8)Ca3FeRe trigonal bipyramids,  a cornercorner with one O(10)Ca2FeRe trigonal pyramid,  a cornercorner with one O(7)Ca2FeRe trigonal pyramid,  an edgeedge with one O(3)Ca2FeRe tetrahedra,  an edgeedge with one O(4)Ca2FeRe tetrahedra, and  an edgeedge with one O(7)Ca2FeRe trigonal pyramid.