YIr2Si 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 two equivalent Y(1), twelve equivalent Ir(1), three equivalent Si(1), and three equivalent Si(2) atoms. Ir(1) is bonded in a 12-coordinate geometry to two equivalent Y(2), three equivalent Y(1), four equivalent Ir(1), one Si(1), one Si(2), and one Si(3) atom. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to three equivalent Y(2) and six equivalent Ir(1) atoms. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to three equivalent Y(2) and six equivalent Ir(1) atoms. In the third Si site, Si(3) is bonded in a distorted cuboctahedral geometry to six equivalent Ir(1) atoms.
YIr2Si 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 3.20 Å. There are three shorter (3.04 Å) and six longer (3.12 Å) Y(1)-Ir(1) bond lengths. In the second Y site, Y(2) is bonded in a 20-coordinate geometry to two equivalent Y(1), twelve equivalent Ir(1), three equivalent Si(1), and three equivalent Si(2) atoms. All Y(2)-Ir(1) bond lengths are 3.33 Å. All Y(2)-Si(1) bond lengths are 3.22 Å. All Y(2)-Si(2) bond lengths are 3.22 Å. Ir(1) is bonded in a 12-coordinate geometry to two equivalent Y(2), three equivalent Y(1), four equivalent Ir(1), one Si(1), one Si(2), and one Si(3) atom. There are two shorter (2.78 Å) and two longer (2.80 Å) Ir(1)-Ir(1) bond lengths. The Ir(1)-Si(1) bond length is 2.43 Å. The Ir(1)-Si(2) bond length is 2.42 Å. The Ir(1)-Si(3) bond length is 2.56 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to three equivalent Y(2) and six equivalent Ir(1) atoms. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to three equivalent Y(2) and six equivalent Ir(1) atoms. In the third Si site, Si(3) is bonded in a distorted cuboctahedral geometry to six equivalent Ir(1) atoms.