Li2FeSi3O8 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(4), one O(5), and one O(8) atom to form distorted LiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the second Li site, Li(2) is bonded in a trigonal non-coplanar geometry to one O(1), one O(6), and one O(7) atom. Fe(1) is bonded to one O(1), one O(4), one O(6), and one O(8) atom to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Li(1), one Si(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(1), and one Si(3) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Si(1), and one Si(3) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(3) atom.
Li2FeSi3O8 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(4), one O(5), and one O(8) atom to form distorted LiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Li(1)-O(2) bond length is 2.40 Å. The Li(1)-O(4) bond length is 1.93 Å. The Li(1)-O(5) bond length is 2.13 Å. The Li(1)-O(8) bond length is 1.92 Å. In the second Li site, Li(2) is bonded in a trigonal non-coplanar geometry to one O(1), one O(6), and one O(7) atom. The Li(2)-O(1) bond length is 1.90 Å. The Li(2)-O(6) bond length is 1.89 Å. The Li(2)-O(7) bond length is 2.11 Å. Fe(1) is bonded to one O(1), one O(4), one O(6), and one O(8) atom to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Fe(1)-O(1) bond length is 2.00 Å. The Fe(1)-O(4) bond length is 1.98 Å. The Fe(1)-O(6) bond length is 2.02 Å. The Fe(1)-O(8) bond length is 2.03 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Si(1)-O(2) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(5) bond length is 1.67 Å. The Si(1)-O(7) bond length is 1.68 Å. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The Si(2)-O(1) bond length is 1.61 Å. The Si(2)-O(2) bond length is 1.69 Å. The Si(2)-O(3) bond length is 1.68 Å. The Si(2)-O(4) bond length is 1.60 Å. In the third Si site, Si(3) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The Si(3)-O(5) bond length is 1.71 Å. The Si(3)-O(6) bond length is 1.61 Å. The Si(3)-O(7) bond length is 1.70 Å. The Si(3)-O(8) bond length is 1.61 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Li(1), one Si(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(1), and one Si(3) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Si(1), and one Si(3) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(3) atom.