LaFe8Si5 crystallizes in the monoclinic C2/m space group. La(1) is bonded in a 24-coordinate geometry to two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), four equivalent Fe(1), four equivalent Fe(2), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(5), two equivalent Si(1), and two equivalent Si(2) atoms. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to two equivalent La(1), one Fe(3), one Fe(7), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. In the third Fe site, Fe(3) is bonded in a cuboctahedral geometry to two equivalent Fe(7), four equivalent Fe(2), two equivalent Si(3), and four equivalent Si(1) atoms. In the fourth Fe site, Fe(4) is bonded in a cuboctahedral geometry to two equivalent Fe(5), two equivalent Fe(6), four equivalent Fe(1), and four equivalent Si(2) atoms. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(6), two equivalent Fe(1), two equivalent Fe(7), two equivalent Si(1), and two equivalent Si(2) atoms. In the sixth Fe site, Fe(6) is bonded in a 2-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. In the seventh Fe site, Fe(7) is bonded in a 12-coordinate geometry to two equivalent La(1), one Fe(3), two equivalent Fe(2), two equivalent Fe(5), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to two equivalent La(1), one Fe(3), one Fe(5), one Fe(6), one Fe(7), two equivalent Fe(1), two equivalent Fe(2), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 11-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(5), one Fe(6), one Fe(7), two equivalent Fe(1), two equivalent Fe(2), and one Si(3) atom. In the third Si site, Si(3) is bonded in a 12-coordinate geometry to two equivalent La(1), one Fe(3), one Fe(7), two equivalent Fe(2), two equivalent Fe(6), two equivalent Si(1), and two equivalent Si(2) atoms.
LaFe8Si5 crystallizes in the monoclinic C2/m space group. La(1) is bonded in a 24-coordinate geometry to two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), four equivalent Fe(1), four equivalent Fe(2), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms. Both La(1)-Fe(5) bond lengths are 3.37 Å. Both La(1)-Fe(6) bond lengths are 3.27 Å. Both La(1)-Fe(7) bond lengths are 3.36 Å. There are two shorter (3.17 Å) and two longer (3.23 Å) La(1)-Fe(1) bond lengths. There are two shorter (3.18 Å) and two longer (3.21 Å) La(1)-Fe(2) bond lengths. Both La(1)-Si(3) bond lengths are 3.36 Å. There are two shorter (3.19 Å) and two longer (3.29 Å) La(1)-Si(1) bond lengths. There are two shorter (3.23 Å) and two longer (3.28 Å) La(1)-Si(2) bond lengths. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(5), two equivalent Si(1), and two equivalent Si(2) atoms. The Fe(1)-Fe(4) bond length is 2.48 Å. The Fe(1)-Fe(5) bond length is 2.53 Å. There is one shorter (2.34 Å) and one longer (2.36 Å) Fe(1)-Si(1) bond length. There is one shorter (2.37 Å) and one longer (2.40 Å) Fe(1)-Si(2) bond length. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to two equivalent La(1), one Fe(3), one Fe(7), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. The Fe(2)-Fe(3) bond length is 2.49 Å. The Fe(2)-Fe(7) bond length is 2.51 Å. The Fe(2)-Si(3) bond length is 2.46 Å. There is one shorter (2.40 Å) and one longer (2.46 Å) Fe(2)-Si(1) bond length. There is one shorter (2.35 Å) and one longer (2.36 Å) Fe(2)-Si(2) bond length. In the third Fe site, Fe(3) is bonded in a cuboctahedral geometry to two equivalent Fe(7), four equivalent Fe(2), two equivalent Si(3), and four equivalent Si(1) atoms. Both Fe(3)-Fe(7) bond lengths are 2.41 Å. Both Fe(3)-Si(3) bond lengths are 2.33 Å. All Fe(3)-Si(1) bond lengths are 2.38 Å. In the fourth Fe site, Fe(4) is bonded in a cuboctahedral geometry to two equivalent Fe(5), two equivalent Fe(6), four equivalent Fe(1), and four equivalent Si(2) atoms. Both Fe(4)-Fe(5) bond lengths are 2.41 Å. Both Fe(4)-Fe(6) bond lengths are 2.47 Å. All Fe(4)-Si(2) bond lengths are 2.35 Å. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(6), two equivalent Fe(1), two equivalent Fe(7), two equivalent Si(1), and two equivalent Si(2) atoms. The Fe(5)-Fe(6) bond length is 2.66 Å. There is one shorter (2.33 Å) and one longer (2.34 Å) Fe(5)-Fe(7) bond length. Both Fe(5)-Si(1) bond lengths are 2.47 Å. Both Fe(5)-Si(2) bond lengths are 2.53 Å. In the sixth Fe site, Fe(6) is bonded in a 2-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. Both Fe(6)-Si(1) bond lengths are 2.60 Å. Both Fe(6)-Si(2) bond lengths are 2.59 Å. There is one shorter (2.31 Å) and one longer (2.32 Å) Fe(6)-Si(3) bond length. In the seventh Fe site, Fe(7) is bonded in a 12-coordinate geometry to two equivalent La(1), one Fe(3), two equivalent Fe(2), two equivalent Fe(5), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. The Fe(7)-Si(3) bond length is 2.51 Å. Both Fe(7)-Si(1) bond lengths are 2.53 Å. Both Fe(7)-Si(2) bond lengths are 2.51 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to two equivalent La(1), one Fe(3), one Fe(5), one Fe(6), one Fe(7), two equivalent Fe(1), two equivalent Fe(2), and one Si(3) atom. The Si(1)-Si(3) bond length is 2.59 Å. In the second Si site, Si(2) is bonded in a 11-coordinate geometry to two equivalent La(1), one Fe(4), one Fe(5), one Fe(6), one Fe(7), two equivalent Fe(1), two equivalent Fe(2), and one Si(3) atom. The Si(2)-Si(3) bond length is 2.58 Å. In the third Si site, Si(3) is bonded in a 12-coordinate geometry to two equivalent La(1), one Fe(3), one Fe(7), two equivalent Fe(2), two equivalent Fe(6), two equivalent Si(1), and two equivalent Si(2) atoms.