TbNiSi2 crystallizes in the orthorhombic Cmcm space group. Tb(1) is bonded in a 14-coordinate geometry to four equivalent Ni(1), four equivalent Si(1), and six equivalent Si(2) atoms. Ni(1) is bonded in a 9-coordinate geometry to four equivalent Tb(1), one Si(2), and four equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to four equivalent Tb(1) and four equivalent Ni(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Tb(1), one Ni(1), and two equivalent Si(2) atoms.
TbNiSi2 crystallizes in the orthorhombic Cmcm space group. Tb(1) is bonded in a 14-coordinate geometry to four equivalent Ni(1), four equivalent Si(1), and six equivalent Si(2) atoms. All Tb(1)-Ni(1) bond lengths are 3.05 Å. There are two shorter (3.07 Å) and two longer (3.09 Å) Tb(1)-Si(1) bond lengths. There are four shorter (3.01 Å) and two longer (3.12 Å) Tb(1)-Si(2) bond lengths. Ni(1) is bonded in a 9-coordinate geometry to four equivalent Tb(1), one Si(2), and four equivalent Si(1) atoms. The Ni(1)-Si(2) bond length is 2.25 Å. There are two shorter (2.30 Å) and two longer (2.32 Å) Ni(1)-Si(1) bond lengths. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to four equivalent Tb(1) and four equivalent Ni(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Tb(1), one Ni(1), and two equivalent Si(2) atoms. Both Si(2)-Si(2) bond lengths are 2.38 Å.