Ca2Fe2(SiO3)5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(11), one O(15), one O(6), one O(8), one O(9), and two equivalent O(5) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(1), one O(13), one O(14), one O(2), one O(3), one O(7), and two equivalent O(12) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(11), one O(2), one O(3), one O(9), and two equivalent O(13) atoms to form FeO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(14), one O(3), one O(5), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-66°. In the second Si site, Si(2) is bonded to one O(15), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. In the third Si site, Si(3) is bonded to one O(15), one O(7), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-48°. In the fourth Si site, Si(4) is bonded to one O(10), one O(11), one O(12), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 25-61°. In the fifth Si site, Si(5) is bonded to one O(1), one O(12), one O(13), and one O(14) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-65°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Si(1), and one Si(5) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(2), one Fe(1), and one Si(1) atom. In the third O site, O(3) is bonded to one Ca(2), one Fe(1), one Fe(2), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si tetrahedra. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ca(2), one Si(3), and one Si(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ca(1), one Fe(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one Si(3) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Fe(2) and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(1), one Fe(2), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to two equivalent Ca(2), one Si(4), and one Si(5) atom. In the thirteenth O site, O(13) is bonded to one Ca(2), two equivalent Fe(1), and one Si(5) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si tetrahedra. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Ca(2), one Fe(2), and one Si(5) atom. In the fifteenth O site, O(15) is bonded in a distorted bent 120 degrees geometry to one Ca(1), one Si(2), and one Si(3) atom.
Ca2Fe2(SiO3)5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(11), one O(15), one O(6), one O(8), one O(9), and two equivalent O(5) atoms. The Ca(1)-O(11) bond length is 2.68 Å. The Ca(1)-O(15) bond length is 2.96 Å. The Ca(1)-O(6) bond length is 2.13 Å. The Ca(1)-O(8) bond length is 2.34 Å. The Ca(1)-O(9) bond length is 2.57 Å. There is one shorter (2.39 Å) and one longer (2.75 Å) Ca(1)-O(5) bond length. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(1), one O(13), one O(14), one O(2), one O(3), one O(7), and two equivalent O(12) atoms. The Ca(2)-O(1) bond length is 2.40 Å. The Ca(2)-O(13) bond length is 2.38 Å. The Ca(2)-O(14) bond length is 2.35 Å. The Ca(2)-O(2) bond length is 2.41 Å. The Ca(2)-O(3) bond length is 2.37 Å. The Ca(2)-O(7) bond length is 2.74 Å. There is one shorter (2.48 Å) and one longer (2.96 Å) Ca(2)-O(12) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(11), one O(2), one O(3), one O(9), and two equivalent O(13) atoms to form FeO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The Fe(1)-O(11) bond length is 2.01 Å. The Fe(1)-O(2) bond length is 2.02 Å. The Fe(1)-O(3) bond length is 2.13 Å. The Fe(1)-O(9) bond length is 1.92 Å. There is one shorter (2.13 Å) and one longer (2.34 Å) Fe(1)-O(13) bond length. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(14), one O(3), one O(5), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The Fe(2)-O(10) bond length is 1.90 Å. The Fe(2)-O(11) bond length is 2.28 Å. The Fe(2)-O(14) bond length is 2.07 Å. The Fe(2)-O(3) bond length is 2.24 Å. The Fe(2)-O(5) bond length is 1.99 Å. The Fe(2)-O(8) bond length is 1.92 Å. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-66°. The Si(1)-O(1) bond length is 1.68 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.61 Å. In the second Si site, Si(2) is bonded to one O(15), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. The Si(2)-O(15) bond length is 1.69 Å. The Si(2)-O(4) bond length is 1.66 Å. The Si(2)-O(5) bond length is 1.67 Å. The Si(2)-O(6) bond length is 1.57 Å. In the third Si site, Si(3) is bonded to one O(15), one O(7), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-48°. The Si(3)-O(15) bond length is 1.65 Å. The Si(3)-O(7) bond length is 1.68 Å. The Si(3)-O(8) bond length is 1.62 Å. The Si(3)-O(9) bond length is 1.63 Å. In the fourth Si site, Si(4) is bonded to one O(10), one O(11), one O(12), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 25-61°. The Si(4)-O(10) bond length is 1.58 Å. The Si(4)-O(11) bond length is 1.65 Å. The Si(4)-O(12) bond length is 1.68 Å. The Si(4)-O(7) bond length is 1.66 Å. In the fifth Si site, Si(5) is bonded to one O(1), one O(12), one O(13), and one O(14) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-65°. The Si(5)-O(1) bond length is 1.64 Å. The Si(5)-O(12) bond length is 1.67 Å. The Si(5)-O(13) bond length is 1.65 Å. The Si(5)-O(14) bond length is 1.61 Å. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Si(1), and one Si(5) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(2), one Fe(1), and one Si(1) atom. In the third O site, O(3) is bonded to one Ca(2), one Fe(1), one Fe(2), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si tetrahedra. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ca(2), one Si(3), and one Si(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ca(1), one Fe(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one Si(3) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Fe(2) and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(1), one Fe(2), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to two equivalent Ca(2), one Si(4), and one Si(5) atom. In the thirteenth O site, O(13) is bonded to one Ca(2), two equivalent Fe(1), and one Si(5) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si tetrahedra. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Ca(2), one Fe(2), and one Si(5) atom. In the fifteenth O site, O(15) is bonded in a distorted bent 120 degrees geometry to one Ca(1), one Si(2), and one Si(3) atom.