Li2Fe3Si3O10 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted LiO5 square pyramids that share  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Li(1)O5 square pyramid, and  an edgeedge with one Si(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms. In the second Fe site, Fe(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Li(1)O5 square pyramids, and edges with two equivalent Si(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Li(1)O5 square pyramid,  a cornercorner with one Si(2)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Li(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 58°. In the second Si site, Si(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with six equivalent Li(1)O5 square pyramids and corners with two equivalent Si(1)O4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), one Fe(1), and one Si(2) atom to form distorted OLi2FeSi tetrahedra that share  a cornercorner with one O(1)Li2FeSi tetrahedra, corners with three equivalent O(3)LiFe2Si tetrahedra, corners with two equivalent O(5)Fe3Si trigonal pyramids, and  an edgeedge with one O(1)Li2FeSi tetrahedra. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Li(1), one Fe(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded to one Li(1), one Fe(1), one Fe(2), and one Si(1) atom to form distorted OLiFe2Si tetrahedra that share  a cornercorner with one O(3)LiFe2Si tetrahedra, corners with three equivalent O(1)Li2FeSi tetrahedra, corners with three equivalent O(5)Fe3Si trigonal pyramids, and  an edgeedge with one O(5)Fe3Si trigonal pyramid. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Li(1), one Fe(1), one Fe(2), and one Si(1) atom. In the fifth O site, O(5) is bonded to one Fe(2), two equivalent Fe(1), and one Si(1) atom to form distorted OFe3Si trigonal pyramids that share corners with two equivalent O(1)Li2FeSi tetrahedra, corners with three equivalent O(3)LiFe2Si tetrahedra, corners with three equivalent O(5)Fe3Si trigonal pyramids, and  an edgeedge with one O(3)LiFe2Si tetrahedra.
Li2Fe3Si3O10 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted LiO5 square pyramids that share  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Li(1)O5 square pyramid, and  an edgeedge with one Si(1)O4 tetrahedra. The Li(1)-O(2) bond length is 2.45 Å. The Li(1)-O(3) bond length is 2.01 Å. The Li(1)-O(4) bond length is 2.29 Å. There is one shorter (2.03 Å) and one longer (2.30 Å) Li(1)-O(1) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms. The Fe(1)-O(1) bond length is 2.14 Å. The Fe(1)-O(2) bond length is 2.67 Å. The Fe(1)-O(3) bond length is 2.22 Å. The Fe(1)-O(4) bond length is 2.09 Å. There is one shorter (2.12 Å) and one longer (2.25 Å) Fe(1)-O(5) bond length. In the second Fe site, Fe(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Li(1)O5 square pyramids, and edges with two equivalent Si(1)O4 tetrahedra. Both Fe(2)-O(3) bond lengths are 2.10 Å. Both Fe(2)-O(4) bond lengths are 2.18 Å. Both Fe(2)-O(5) bond lengths are 2.25 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Li(1)O5 square pyramid,  a cornercorner with one Si(2)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Li(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 58°. The Si(1)-O(2) bond length is 1.67 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.64 Å. The Si(1)-O(5) bond length is 1.65 Å. In the second Si site, Si(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with six equivalent Li(1)O5 square pyramids and corners with two equivalent Si(1)O4 tetrahedra. Both Si(2)-O(1) bond lengths are 1.63 Å. Both Si(2)-O(2) bond lengths are 1.67 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), one Fe(1), and one Si(2) atom to form distorted OLi2FeSi tetrahedra that share  a cornercorner with one O(1)Li2FeSi tetrahedra, corners with three equivalent O(3)LiFe2Si tetrahedra, corners with two equivalent O(5)Fe3Si trigonal pyramids, and  an edgeedge with one O(1)Li2FeSi tetrahedra. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Li(1), one Fe(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded to one Li(1), one Fe(1), one Fe(2), and one Si(1) atom to form distorted OLiFe2Si tetrahedra that share  a cornercorner with one O(3)LiFe2Si tetrahedra, corners with three equivalent O(1)Li2FeSi tetrahedra, corners with three equivalent O(5)Fe3Si trigonal pyramids, and  an edgeedge with one O(5)Fe3Si trigonal pyramid. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Li(1), one Fe(1), one Fe(2), and one Si(1) atom. In the fifth O site, O(5) is bonded to one Fe(2), two equivalent Fe(1), and one Si(1) atom to form distorted OFe3Si trigonal pyramids that share corners with two equivalent O(1)Li2FeSi tetrahedra, corners with three equivalent O(3)LiFe2Si tetrahedra, corners with three equivalent O(5)Fe3Si trigonal pyramids, and  an edgeedge with one O(3)LiFe2Si tetrahedra.