Y4Ir9Si5 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 9-coordinate geometry to one Y(2) and nine equivalent Ir(1) atoms. In the second Y site, Y(2) is bonded in a 20-coordinate geometry to one Y(1), one Y(2), six equivalent Ir(1), six equivalent Ir(2), three equivalent Si(2), and three equivalent Si(3) atoms. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded in a 6-coordinate geometry to two equivalent Y(2), three equivalent Y(1), one Si(1), one Si(2), and one Si(3) atom. In the second Ir site, Ir(2) is bonded in a 4-coordinate geometry to four equivalent Y(2), two equivalent Si(2), and two equivalent Si(3) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted cuboctahedral geometry to six equivalent Ir(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Y(2), three equivalent Ir(1), and three equivalent Ir(2) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to three equivalent Y(2), three equivalent Ir(1), and three equivalent Ir(2) atoms.
Y4Ir9Si5 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 9-coordinate geometry to one Y(2) and nine equivalent Ir(1) atoms. The Y(1)-Y(2) bond length is 3.30 Å. There are three shorter (3.03 Å) and six longer (3.08 Å) Y(1)-Ir(1) bond lengths. In the second Y site, Y(2) is bonded in a 20-coordinate geometry to one Y(1), one Y(2), six equivalent Ir(1), six equivalent Ir(2), three equivalent Si(2), and three equivalent Si(3) atoms. The Y(2)-Y(2) bond length is 3.44 Å. All Y(2)-Ir(1) bond lengths are 3.38 Å. All Y(2)-Ir(2) bond lengths are 3.25 Å. All Y(2)-Si(2) bond lengths are 3.20 Å. All Y(2)-Si(3) bond lengths are 3.20 Å. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded in a 6-coordinate geometry to two equivalent Y(2), three equivalent Y(1), one Si(1), one Si(2), and one Si(3) atom. The Ir(1)-Si(1) bond length is 2.54 Å. The Ir(1)-Si(2) bond length is 2.41 Å. The Ir(1)-Si(3) bond length is 2.41 Å. In the second Ir site, Ir(2) is bonded in a 4-coordinate geometry to four equivalent Y(2), two equivalent Si(2), and two equivalent Si(3) atoms. Both Ir(2)-Si(2) bond lengths are 2.44 Å. Both Ir(2)-Si(3) bond lengths are 2.45 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted cuboctahedral geometry to six equivalent Ir(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Y(2), three equivalent Ir(1), and three equivalent Ir(2) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to three equivalent Y(2), three equivalent Ir(1), and three equivalent Ir(2) atoms.