Li3FeS3 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to two equivalent S(1) and two equivalent S(3) atoms. In the second Li site, Li(2) is bonded to two equivalent S(1) and two equivalent S(3) atoms to form distorted LiS4 trigonal pyramids that share corners with four equivalent Fe(1)Li2S4 tetrahedra, corners with two equivalent Li(2)S4 trigonal pyramids, and  an edgeedge with one Li(2)S4 trigonal pyramid. In the third Li site, Li(3) is bonded in a 7-coordinate geometry to two equivalent Fe(1), one S(3), two equivalent S(1), and two equivalent S(2) atoms. Fe(1) is bonded to two equivalent Li(3), one S(1), one S(3), and two equivalent S(2) atoms to form distorted FeLi2S4 tetrahedra that share corners with two equivalent S(1)Li6Fe pentagonal bipyramids, corners with two equivalent S(3)Li5Fe pentagonal pyramids, corners with two equivalent Fe(1)Li2S4 tetrahedra, corners with four equivalent Li(2)S4 trigonal pyramids,  an edgeedge with one S(1)Li6Fe pentagonal bipyramid, and  an edgeedge with one Fe(1)Li2S4 tetrahedra. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Li(1), two equivalent Li(2), two equivalent Li(3), and one Fe(1) atom to form distorted SLi6Fe pentagonal bipyramids that share corners with two equivalent S(1)Li6Fe pentagonal bipyramids, corners with three equivalent S(3)Li5Fe pentagonal pyramids, corners with two equivalent Fe(1)Li2S4 tetrahedra, edges with two equivalent S(1)Li6Fe pentagonal bipyramids, edges with four equivalent S(3)Li5Fe pentagonal pyramids, and  an edgeedge with one Fe(1)Li2S4 tetrahedra. In the second S site, S(2) is bonded in a 4-coordinate geometry to two equivalent Li(3) and two equivalent Fe(1) atoms. In the third S site, S(3) is bonded to one Li(3), two equivalent Li(1), two equivalent Li(2), and one Fe(1) atom to form distorted SLi5Fe pentagonal pyramids that share corners with three equivalent S(1)Li6Fe pentagonal bipyramids, corners with two equivalent Fe(1)Li2S4 tetrahedra, edges with four equivalent S(1)Li6Fe pentagonal bipyramids, and edges with two equivalent S(3)Li5Fe pentagonal pyramids.
Li3FeS3 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to two equivalent S(1) and two equivalent S(3) atoms. There is one shorter (2.45 Å) and one longer (2.66 Å) Li(1)-S(1) bond length. There is one shorter (2.42 Å) and one longer (2.63 Å) Li(1)-S(3) bond length. In the second Li site, Li(2) is bonded to two equivalent S(1) and two equivalent S(3) atoms to form distorted LiS4 trigonal pyramids that share corners with four equivalent Fe(1)Li2S4 tetrahedra, corners with two equivalent Li(2)S4 trigonal pyramids, and  an edgeedge with one Li(2)S4 trigonal pyramid. There is one shorter (2.55 Å) and one longer (2.57 Å) Li(2)-S(1) bond length. There is one shorter (2.53 Å) and one longer (2.59 Å) Li(2)-S(3) bond length. In the third Li site, Li(3) is bonded in a 7-coordinate geometry to two equivalent Fe(1), one S(3), two equivalent S(1), and two equivalent S(2) atoms. There is one shorter (2.80 Å) and one longer (2.94 Å) Li(3)-Fe(1) bond length. The Li(3)-S(3) bond length is 2.48 Å. There is one shorter (2.65 Å) and one longer (2.78 Å) Li(3)-S(1) bond length. There is one shorter (2.46 Å) and one longer (2.80 Å) Li(3)-S(2) bond length. Fe(1) is bonded to two equivalent Li(3), one S(1), one S(3), and two equivalent S(2) atoms to form distorted FeLi2S4 tetrahedra that share corners with two equivalent S(1)Li6Fe pentagonal bipyramids, corners with two equivalent S(3)Li5Fe pentagonal pyramids, corners with two equivalent Fe(1)Li2S4 tetrahedra, corners with four equivalent Li(2)S4 trigonal pyramids,  an edgeedge with one S(1)Li6Fe pentagonal bipyramid, and  an edgeedge with one Fe(1)Li2S4 tetrahedra. The Fe(1)-S(1) bond length is 2.22 Å. The Fe(1)-S(3) bond length is 2.21 Å. There is one shorter (2.22 Å) and one longer (2.23 Å) Fe(1)-S(2) bond length. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Li(1), two equivalent Li(2), two equivalent Li(3), and one Fe(1) atom to form distorted SLi6Fe pentagonal bipyramids that share corners with two equivalent S(1)Li6Fe pentagonal bipyramids, corners with three equivalent S(3)Li5Fe pentagonal pyramids, corners with two equivalent Fe(1)Li2S4 tetrahedra, edges with two equivalent S(1)Li6Fe pentagonal bipyramids, edges with four equivalent S(3)Li5Fe pentagonal pyramids, and  an edgeedge with one Fe(1)Li2S4 tetrahedra. In the second S site, S(2) is bonded in a 4-coordinate geometry to two equivalent Li(3) and two equivalent Fe(1) atoms. In the third S site, S(3) is bonded to one Li(3), two equivalent Li(1), two equivalent Li(2), and one Fe(1) atom to form distorted SLi5Fe pentagonal pyramids that share corners with three equivalent S(1)Li6Fe pentagonal bipyramids, corners with two equivalent Fe(1)Li2S4 tetrahedra, edges with four equivalent S(1)Li6Fe pentagonal bipyramids, and edges with two equivalent S(3)Li5Fe pentagonal pyramids.