UNi2Si3 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 16-coordinate geometry to four equivalent Ni(1), four equivalent Ni(2), four equivalent Si(1), and four equivalent Si(2) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent U(1), four equivalent Ni(1), and four equivalent Si(2) atoms to form a mixture of distorted corner and face-sharing NiU4Si4Ni4 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(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 9-coordinate geometry to two equivalent U(1), two equivalent Ni(2), and five equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Ni(2), and four equivalent Ni(1) atoms.
UNi2Si3 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 16-coordinate geometry to four equivalent Ni(1), four equivalent Ni(2), four equivalent Si(1), and four equivalent Si(2) atoms. All U(1)-Ni(1) bond lengths are 3.06 Å. All U(1)-Ni(2) bond lengths are 2.99 Å. All U(1)-Si(1) bond lengths are 3.06 Å. All U(1)-Si(2) bond lengths are 2.96 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent U(1), four equivalent Ni(1), and four equivalent Si(2) atoms to form a mixture of distorted corner and face-sharing NiU4Si4Ni4 cuboctahedra. All Ni(1)-Ni(1) bond lengths are 2.75 Å. All Ni(1)-Si(2) bond lengths are 2.32 Å. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(2), and four equivalent Si(1) atoms. The Ni(2)-Si(2) bond length is 2.29 Å. All Ni(2)-Si(1) bond lengths are 2.27 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(1), two equivalent Ni(2), and five equivalent Si(1) atoms. There is one shorter (2.34 Å) and four longer (2.75 Å) Si(1)-Si(1) bond lengths. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Ni(2), and four equivalent Ni(1) atoms.