ThNiSi2 crystallizes in the orthorhombic Cmcm space group. Th(1) is bonded in a 14-coordinate geometry to four equivalent Ni(1), four equivalent Si(2), and six equivalent Si(1) atoms. Ni(1) is bonded in a 9-coordinate geometry to four equivalent Th(1), one Si(1), and four equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to six equivalent Th(1), one Ni(1), and two equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to four equivalent Th(1) and four equivalent Ni(1) atoms.
ThNiSi2 crystallizes in the orthorhombic Cmcm space group. Th(1) is bonded in a 14-coordinate geometry to four equivalent Ni(1), four equivalent Si(2), and six equivalent Si(1) atoms. All Th(1)-Ni(1) bond lengths are 3.15 Å. There are two shorter (3.10 Å) and two longer (3.14 Å) Th(1)-Si(2) bond lengths. There are four shorter (3.11 Å) and two longer (3.16 Å) Th(1)-Si(1) bond lengths. Ni(1) is bonded in a 9-coordinate geometry to four equivalent Th(1), one Si(1), and four equivalent Si(2) atoms. The Ni(1)-Si(1) bond length is 2.31 Å. All Ni(1)-Si(2) bond lengths are 2.35 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to six equivalent Th(1), one Ni(1), and two equivalent Si(1) atoms. Both Si(1)-Si(1) bond lengths are 2.42 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to four equivalent Th(1) and four equivalent Ni(1) atoms.