Li2Fe5(Si2O7)2 crystallizes in the triclinic P-1 space group. Li(1) is bonded in a 3-coordinate geometry to one Fe(3), one O(1), one O(4), and one O(5) atom. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 2-coordinate geometry to two equivalent O(2) and two equivalent O(5) atoms. In the second Fe site, Fe(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(7) atom. In the third Fe site, Fe(3) is bonded in a 7-coordinate geometry to one Li(1), one O(2), one O(3), one O(4), one O(7), and two equivalent O(6) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(4), and one O(7) atom. In the second Si site, Si(2) is bonded in a 2-coordinate geometry to one O(1) and one O(6) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(2), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Fe(3) and one Si(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Li(1), one Fe(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to one Li(1), one Fe(1), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a 1-coordinate geometry to two equivalent Fe(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Fe(2), one Fe(3), and one Si(1) atom.
Li2Fe5(Si2O7)2 crystallizes in the triclinic P-1 space group. Li(1) is bonded in a 3-coordinate geometry to one Fe(3), one O(1), one O(4), and one O(5) atom. The Li(1)-Fe(3) bond length is 2.78 Å. The Li(1)-O(1) bond length is 1.73 Å. The Li(1)-O(4) bond length is 2.05 Å. The Li(1)-O(5) bond length is 1.86 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 2-coordinate geometry to two equivalent O(2) and two equivalent O(5) atoms. Both Fe(1)-O(2) bond lengths are 2.55 Å. Both Fe(1)-O(5) bond lengths are 1.99 Å. In the second Fe site, Fe(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(7) atom. The Fe(2)-O(1) bond length is 1.89 Å. The Fe(2)-O(2) bond length is 1.87 Å. The Fe(2)-O(5) bond length is 2.63 Å. The Fe(2)-O(7) bond length is 2.32 Å. In the third Fe site, Fe(3) is bonded in a 7-coordinate geometry to one Li(1), one O(2), one O(3), one O(4), one O(7), and two equivalent O(6) atoms. The Fe(3)-O(2) bond length is 2.55 Å. The Fe(3)-O(3) bond length is 2.64 Å. The Fe(3)-O(4) bond length is 2.46 Å. The Fe(3)-O(7) bond length is 1.99 Å. There is one shorter (2.25 Å) and one longer (2.44 Å) Fe(3)-O(6) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(4), and one O(7) atom. The Si(1)-O(2) bond length is 2.20 Å. The Si(1)-O(3) bond length is 1.44 Å. The Si(1)-O(4) bond length is 1.23 Å. The Si(1)-O(7) bond length is 2.27 Å. In the second Si site, Si(2) is bonded in a 2-coordinate geometry to one O(1) and one O(6) atom. The Si(2)-O(1) bond length is 1.31 Å. The Si(2)-O(6) bond length is 1.44 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(2), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Fe(3) and one Si(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Li(1), one Fe(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to one Li(1), one Fe(1), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a 1-coordinate geometry to two equivalent Fe(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Fe(2), one Fe(3), and one Si(1) atom.