LiFeSi2O6 crystallizes in the monoclinic Cc space group. Li(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form distorted LiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, and corners with three equivalent Si(2)O4 tetrahedra. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with three equivalent Li(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(5), and one O(6) 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(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with three equivalent Li(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom.
LiFeSi2O6 crystallizes in the monoclinic Cc space group. Li(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form distorted LiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, and corners with three equivalent Si(2)O4 tetrahedra. The Li(1)-O(1) bond length is 2.00 Å. The Li(1)-O(2) bond length is 1.99 Å. The Li(1)-O(3) bond length is 2.07 Å. The Li(1)-O(5) bond length is 2.23 Å. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with three equivalent Li(1)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.90 Å. The Fe(1)-O(2) bond length is 1.91 Å. The Fe(1)-O(3) bond length is 1.91 Å. The Fe(1)-O(4) bond length is 1.85 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(5), and one O(6) 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(2)O4 tetrahedra. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.62 Å. The Si(1)-O(5) bond length is 1.67 Å. The Si(1)-O(6) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with three equivalent Li(1)O4 tetrahedra. The Si(2)-O(2) bond length is 1.63 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(5) bond length is 1.67 Å. The Si(2)-O(6) bond length is 1.63 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom.