Ca3Fe2(WO6)2 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent O(1), three equivalent O(2), and six equivalent O(3) atoms to form CaO12 cuboctahedra that share corners with six equivalent Ca(1)O12 cuboctahedra, faces with three equivalent Ca(2)O12 cuboctahedra, faces with three equivalent Ca(3)O12 cuboctahedra,  a faceface with one W(2)O6 octahedra,  a faceface with one Fe(2)O6 octahedra, faces with three equivalent W(1)O6 octahedra, and faces with three equivalent Fe(1)O6 octahedra. In the second Ca site, Ca(2) is bonded to three equivalent O(3), three equivalent O(4), and six equivalent O(1) atoms to form distorted CaO12 cuboctahedra that share corners with six equivalent Ca(2)O12 cuboctahedra, corners with six equivalent Ca(3)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra,  a faceface with one W(1)O6 octahedra,  a faceface with one Fe(2)O6 octahedra, faces with three equivalent W(2)O6 octahedra, and faces with three equivalent Fe(1)O6 octahedra. In the third Ca site, Ca(3) is bonded to three equivalent O(3), three equivalent O(4), and six equivalent O(2) atoms to form CaO12 cuboctahedra that share corners with six equivalent Ca(2)O12 cuboctahedra, corners with six equivalent Ca(3)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra,  a faceface with one W(2)O6 octahedra,  a faceface with one Fe(1)O6 octahedra, faces with three equivalent W(1)O6 octahedra, and faces with three equivalent Fe(2)O6 octahedra. There are two inequivalent W sites. In the first W site, W(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form WO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra,  a faceface with one Ca(2)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, and faces with three equivalent Ca(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-6°. In the second W site, W(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form WO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra,  a faceface with one Ca(1)O12 cuboctahedra,  a faceface with one Ca(3)O12 cuboctahedra, and faces with three equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-10°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form FeO6 octahedra that share corners with three equivalent W(1)O6 octahedra, corners with three equivalent W(2)O6 octahedra,  a faceface with one Ca(3)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, and faces with three equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-10°. In the second Fe site, Fe(2) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent W(1)O6 octahedra, corners with three equivalent W(2)O6 octahedra,  a faceface with one Ca(1)O12 cuboctahedra,  a faceface with one Ca(2)O12 cuboctahedra, and faces with three equivalent Ca(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-6°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), two equivalent Ca(2), one W(2), and one Fe(1) atom to form a mixture of distorted face, corner, and edge-sharing OCa3FeW square pyramids. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(3), one W(1), and one Fe(2) atom to form a mixture of distorted face, corner, and edge-sharing OCa3FeW square pyramids. In the third O site, O(3) is bonded in a distorted linear geometry to one Ca(2), one Ca(3), two equivalent Ca(1), one W(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Ca(3), one W(2), and one Fe(2) atom.
Ca3Fe2(WO6)2 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent O(1), three equivalent O(2), and six equivalent O(3) atoms to form CaO12 cuboctahedra that share corners with six equivalent Ca(1)O12 cuboctahedra, faces with three equivalent Ca(2)O12 cuboctahedra, faces with three equivalent Ca(3)O12 cuboctahedra,  a faceface with one W(2)O6 octahedra,  a faceface with one Fe(2)O6 octahedra, faces with three equivalent W(1)O6 octahedra, and faces with three equivalent Fe(1)O6 octahedra. All Ca(1)-O(1) bond lengths are 2.54 Å. All Ca(1)-O(2) bond lengths are 2.83 Å. All Ca(1)-O(3) bond lengths are 2.78 Å. In the second Ca site, Ca(2) is bonded to three equivalent O(3), three equivalent O(4), and six equivalent O(1) atoms to form distorted CaO12 cuboctahedra that share corners with six equivalent Ca(2)O12 cuboctahedra, corners with six equivalent Ca(3)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra,  a faceface with one W(1)O6 octahedra,  a faceface with one Fe(2)O6 octahedra, faces with three equivalent W(2)O6 octahedra, and faces with three equivalent Fe(1)O6 octahedra. All Ca(2)-O(3) bond lengths are 2.94 Å. All Ca(2)-O(4) bond lengths are 2.61 Å. All Ca(2)-O(1) bond lengths are 2.79 Å. In the third Ca site, Ca(3) is bonded to three equivalent O(3), three equivalent O(4), and six equivalent O(2) atoms to form CaO12 cuboctahedra that share corners with six equivalent Ca(2)O12 cuboctahedra, corners with six equivalent Ca(3)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra,  a faceface with one W(2)O6 octahedra,  a faceface with one Fe(1)O6 octahedra, faces with three equivalent W(1)O6 octahedra, and faces with three equivalent Fe(2)O6 octahedra. All Ca(3)-O(3) bond lengths are 2.77 Å. All Ca(3)-O(4) bond lengths are 2.80 Å. All Ca(3)-O(2) bond lengths are 2.78 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form WO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra,  a faceface with one Ca(2)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, and faces with three equivalent Ca(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-6°. All W(1)-O(2) bond lengths are 1.92 Å. All W(1)-O(3) bond lengths are 1.95 Å. In the second W site, W(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form WO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra,  a faceface with one Ca(1)O12 cuboctahedra,  a faceface with one Ca(3)O12 cuboctahedra, and faces with three equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-10°. All W(2)-O(1) bond lengths are 1.98 Å. All W(2)-O(4) bond lengths are 1.90 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form FeO6 octahedra that share corners with three equivalent W(1)O6 octahedra, corners with three equivalent W(2)O6 octahedra,  a faceface with one Ca(3)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, and faces with three equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-10°. All Fe(1)-O(1) bond lengths are 1.95 Å. All Fe(1)-O(3) bond lengths are 2.04 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent W(1)O6 octahedra, corners with three equivalent W(2)O6 octahedra,  a faceface with one Ca(1)O12 cuboctahedra,  a faceface with one Ca(2)O12 cuboctahedra, and faces with three equivalent Ca(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-6°. All Fe(2)-O(2) bond lengths are 2.01 Å. All Fe(2)-O(4) bond lengths are 1.99 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), two equivalent Ca(2), one W(2), and one Fe(1) atom to form a mixture of distorted face, corner, and edge-sharing OCa3FeW square pyramids. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(3), one W(1), and one Fe(2) atom to form a mixture of distorted face, corner, and edge-sharing OCa3FeW square pyramids. In the third O site, O(3) is bonded in a distorted linear geometry to one Ca(2), one Ca(3), two equivalent Ca(1), one W(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Ca(3), one W(2), and one Fe(2) atom.