LaSi5 crystallizes in the monoclinic C2/m space group. La(1) is bonded in a 9-coordinate geometry to one Si(5), two equivalent Si(3), two equivalent Si(4), three equivalent Si(1), and four equivalent Si(2) atoms. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to three equivalent La(1), one Si(4), and two equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to four equivalent La(1), one Si(2), and two equivalent Si(5) atoms. In the third Si site, Si(3) is bonded in a 5-coordinate geometry to two equivalent La(1), one Si(3), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 6-coordinate geometry to two equivalent La(1), one Si(1), one Si(5), and two equivalent Si(3) atoms. In the fifth Si site, Si(5) is bonded in a distorted see-saw-like geometry to one La(1), one Si(4), and two equivalent Si(2) atoms.
LaSi5 crystallizes in the monoclinic C2/m space group. La(1) is bonded in a 9-coordinate geometry to one Si(5), two equivalent Si(3), two equivalent Si(4), three equivalent Si(1), and four equivalent Si(2) atoms. The La(1)-Si(5) bond length is 3.19 Å. Both La(1)-Si(3) bond lengths are 3.09 Å. There is one shorter (3.33 Å) and one longer (3.50 Å) La(1)-Si(4) bond length. There are two shorter (3.11 Å) and one longer (3.35 Å) La(1)-Si(1) bond length. There are two shorter (3.18 Å) and two longer (3.21 Å) La(1)-Si(2) bond lengths. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to three equivalent La(1), one Si(4), and two equivalent Si(1) atoms. The Si(1)-Si(4) bond length is 2.35 Å. Both Si(1)-Si(1) bond lengths are 2.41 Å. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to four equivalent La(1), one Si(2), and two equivalent Si(5) atoms. The Si(2)-Si(2) bond length is 2.39 Å. Both Si(2)-Si(5) bond lengths are 2.48 Å. In the third Si site, Si(3) is bonded in a 5-coordinate geometry to two equivalent La(1), one Si(3), and two equivalent Si(4) atoms. The Si(3)-Si(3) bond length is 2.34 Å. Both Si(3)-Si(4) bond lengths are 2.38 Å. In the fourth Si site, Si(4) is bonded in a 6-coordinate geometry to two equivalent La(1), one Si(1), one Si(5), and two equivalent Si(3) atoms. The Si(4)-Si(5) bond length is 2.39 Å. In the fifth Si site, Si(5) is bonded in a distorted see-saw-like geometry to one La(1), one Si(4), and two equivalent Si(2) atoms.