La5Si4 crystallizes in the orthorhombic C222_1 space group. There are six inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), two equivalent Si(2), and two equivalent Si(4) atoms. In the second La site, La(2) is bonded in a 6-coordinate geometry to one Si(2), one Si(4), two equivalent Si(1), and two equivalent Si(3) atoms. In the third La site, La(3) is bonded to one Si(2), one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms to form a mixture of distorted corner, edge, and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 40-50°. In the fourth La site, La(4) is bonded to one Si(1), one Si(4), two equivalent Si(2), and two equivalent Si(3) atoms to form a mixture of distorted corner, edge, and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 40-50°. In the fifth La site, La(5) is bonded to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(4) atoms to form a mixture of corner and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. In the sixth La site, La(6) is bonded to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms to form a mixture of corner and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one La(1), one La(4), one La(5), one La(6), two equivalent La(2), two equivalent La(3), and one Si(4) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one La(2), one La(3), one La(5), one La(6), two equivalent La(1), two equivalent La(4), and one Si(3) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one La(1), one La(3), one La(6), two equivalent La(2), two equivalent La(4), and one Si(2) atom. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one La(2), one La(4), one La(5), two equivalent La(1), two equivalent La(3), and one Si(1) atom.
La5Si4 crystallizes in the orthorhombic C222_1 space group. There are six inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), two equivalent Si(2), and two equivalent Si(4) atoms. The La(1)-Si(1) bond length is 3.20 Å. The La(1)-Si(3) bond length is 3.07 Å. There is one shorter (3.18 Å) and one longer (3.21 Å) La(1)-Si(2) bond length. There is one shorter (3.04 Å) and one longer (3.14 Å) La(1)-Si(4) bond length. In the second La site, La(2) is bonded in a 6-coordinate geometry to one Si(2), one Si(4), two equivalent Si(1), and two equivalent Si(3) atoms. The La(2)-Si(2) bond length is 3.19 Å. The La(2)-Si(4) bond length is 3.06 Å. There is one shorter (3.18 Å) and one longer (3.20 Å) La(2)-Si(1) bond length. There is one shorter (3.05 Å) and one longer (3.13 Å) La(2)-Si(3) bond length. In the third La site, La(3) is bonded to one Si(2), one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms to form a mixture of distorted corner, edge, and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 40-50°. The La(3)-Si(2) bond length is 3.24 Å. The La(3)-Si(3) bond length is 3.28 Å. There is one shorter (3.24 Å) and one longer (3.41 Å) La(3)-Si(1) bond length. There is one shorter (3.19 Å) and one longer (3.33 Å) La(3)-Si(4) bond length. In the fourth La site, La(4) is bonded to one Si(1), one Si(4), two equivalent Si(2), and two equivalent Si(3) atoms to form a mixture of distorted corner, edge, and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 40-50°. The La(4)-Si(1) bond length is 3.26 Å. The La(4)-Si(4) bond length is 3.29 Å. There is one shorter (3.23 Å) and one longer (3.42 Å) La(4)-Si(2) bond length. There is one shorter (3.18 Å) and one longer (3.33 Å) La(4)-Si(3) bond length. In the fifth La site, La(5) is bonded to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(4) atoms to form a mixture of corner and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. Both La(5)-Si(1) bond lengths are 3.25 Å. Both La(5)-Si(2) bond lengths are 3.23 Å. Both La(5)-Si(4) bond lengths are 3.21 Å. In the sixth La site, La(6) is bonded to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms to form a mixture of corner and face-sharing LaSi6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. Both La(6)-Si(1) bond lengths are 3.23 Å. Both La(6)-Si(2) bond lengths are 3.26 Å. Both La(6)-Si(3) bond lengths are 3.20 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one La(1), one La(4), one La(5), one La(6), two equivalent La(2), two equivalent La(3), and one Si(4) atom. The Si(1)-Si(4) bond length is 2.44 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one La(2), one La(3), one La(5), one La(6), two equivalent La(1), two equivalent La(4), and one Si(3) atom. The Si(2)-Si(3) bond length is 2.45 Å. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one La(1), one La(3), one La(6), two equivalent La(2), two equivalent La(4), and one Si(2) atom. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one La(2), one La(4), one La(5), two equivalent La(1), two equivalent La(3), and one Si(1) atom.