Li2Fe(Si2O5)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a distorted see-saw-like geometry to one O(1), one O(10), one O(5), and one O(8) atom. In the second Li site, Li(2) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(9) atom. Fe(1) is bonded to one O(1), one O(10), one O(5), and two equivalent O(8) atoms to form distorted FeO5 square pyramids 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, corners with two equivalent Si(4)O4 tetrahedra, and  an edgeedge with one Fe(1)O5 square pyramid. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(10), one O(2), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(2), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O5 square pyramids,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Li(2), one Si(1), and one Si(3) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Fe(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Li(1), two equivalent Fe(1), and one Si(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Li(2), one Si(3), and one Si(4) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Fe(1), and one Si(2) atom.
Li2Fe(Si2O5)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a distorted see-saw-like geometry to one O(1), one O(10), one O(5), and one O(8) atom. The Li(1)-O(1) bond length is 2.13 Å. The Li(1)-O(10) bond length is 2.22 Å. The Li(1)-O(5) bond length is 2.08 Å. The Li(1)-O(8) bond length is 2.09 Å. In the second Li site, Li(2) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(9) atom. The Li(2)-O(3) bond length is 2.05 Å. The Li(2)-O(4) bond length is 2.03 Å. The Li(2)-O(9) bond length is 2.02 Å. Fe(1) is bonded to one O(1), one O(10), one O(5), and two equivalent O(8) atoms to form distorted FeO5 square pyramids 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, corners with two equivalent Si(4)O4 tetrahedra, and  an edgeedge with one Fe(1)O5 square pyramid. The Fe(1)-O(1) bond length is 2.19 Å. The Fe(1)-O(10) bond length is 2.01 Å. The Fe(1)-O(5) bond length is 2.03 Å. There is one shorter (2.16 Å) and one longer (2.36 Å) Fe(1)-O(8) bond length. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The Si(1)-O(1) bond length is 1.59 Å. The Si(1)-O(3) bond length is 1.68 Å. The Si(1)-O(4) bond length is 1.67 Å. The Si(1)-O(6) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(10), one O(2), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The Si(2)-O(10) bond length is 1.59 Å. The Si(2)-O(2) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.69 Å. The Si(2)-O(7) bond length is 1.65 Å. In the third Si site, Si(3) is bonded to one O(2), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The Si(3)-O(2) bond length is 1.64 Å. The Si(3)-O(3) bond length is 1.68 Å. The Si(3)-O(5) bond length is 1.59 Å. The Si(3)-O(9) bond length is 1.65 Å. In the fourth Si site, Si(4) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O5 square pyramids,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The Si(4)-O(6) bond length is 1.63 Å. The Si(4)-O(7) bond length is 1.64 Å. The Si(4)-O(8) bond length is 1.60 Å. The Si(4)-O(9) bond length is 1.66 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Li(2), one Si(1), and one Si(3) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Fe(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Li(1), two equivalent Fe(1), and one Si(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Li(2), one Si(3), and one Si(4) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Fe(1), and one Si(2) atom.