U2NiCu3Si4 crystallizes in the tetragonal P-4m2 space group. U(1) is bonded in a 16-coordinate geometry to two equivalent Ni(1), two equivalent Cu(1), two equivalent Cu(2), two equivalent Cu(3), four equivalent Si(1), and four equivalent Si(2) atoms. Ni(1) is bonded to four equivalent U(1), four equivalent Cu(2), and four equivalent Si(1) atoms to form distorted NiU4Cu4Si4 cuboctahedra that share corners with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(3)U4Cu4Si4 cuboctahedra, corners with eight equivalent Cu(1)U4Cu4Si4 cuboctahedra, edges with two equivalent Cu(3)U4Cu4Si4 cuboctahedra, faces with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(2)U4Si4Ni4 cuboctahedra. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent U(1), four equivalent Cu(3), and four equivalent Si(2) atoms to form distorted CuU4Cu4Si4 cuboctahedra that share corners with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(2)U4Si4Ni4 cuboctahedra, corners with eight equivalent Ni(1)U4Cu4Si4 cuboctahedra, edges with two equivalent Cu(2)U4Si4Ni4 cuboctahedra, faces with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(3)U4Cu4Si4 cuboctahedra. In the second Cu site, Cu(2) is bonded to four equivalent U(1), four equivalent Ni(1), and four equivalent Si(1) atoms to form distorted CuU4Si4Ni4 cuboctahedra that share corners with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(2)U4Si4Ni4 cuboctahedra, corners with eight equivalent Cu(3)U4Cu4Si4 cuboctahedra, edges with two equivalent Cu(1)U4Cu4Si4 cuboctahedra, faces with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(2)U4Si4Ni4 cuboctahedra. In the third Cu site, Cu(3) is bonded to four equivalent U(1), four equivalent Cu(1), and four equivalent Si(2) atoms to form distorted CuU4Cu4Si4 cuboctahedra that share corners with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(3)U4Cu4Si4 cuboctahedra, corners with eight equivalent Cu(2)U4Si4Ni4 cuboctahedra, edges with two equivalent Ni(1)U4Cu4Si4 cuboctahedra, faces with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(3)U4Cu4Si4 cuboctahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent U(1), two equivalent Ni(1), two equivalent Cu(2), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent U(1), two equivalent Cu(1), two equivalent Cu(3), and one Si(1) atom.
U2NiCu3Si4 crystallizes in the tetragonal P-4m2 space group. U(1) is bonded in a 16-coordinate geometry to two equivalent Ni(1), two equivalent Cu(1), two equivalent Cu(2), two equivalent Cu(3), four equivalent Si(1), and four equivalent Si(2) atoms. Both U(1)-Ni(1) bond lengths are 3.13 Å. Both U(1)-Cu(1) bond lengths are 3.20 Å. Both U(1)-Cu(2) bond lengths are 3.13 Å. Both U(1)-Cu(3) bond lengths are 3.20 Å. All U(1)-Si(1) bond lengths are 3.03 Å. All U(1)-Si(2) bond lengths are 3.02 Å. Ni(1) is bonded to four equivalent U(1), four equivalent Cu(2), and four equivalent Si(1) atoms to form distorted NiU4Cu4Si4 cuboctahedra that share corners with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(3)U4Cu4Si4 cuboctahedra, corners with eight equivalent Cu(1)U4Cu4Si4 cuboctahedra, edges with two equivalent Cu(3)U4Cu4Si4 cuboctahedra, faces with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(2)U4Si4Ni4 cuboctahedra. All Ni(1)-Cu(2) bond lengths are 2.79 Å. All Ni(1)-Si(1) bond lengths are 2.34 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent U(1), four equivalent Cu(3), and four equivalent Si(2) atoms to form distorted CuU4Cu4Si4 cuboctahedra that share corners with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(2)U4Si4Ni4 cuboctahedra, corners with eight equivalent Ni(1)U4Cu4Si4 cuboctahedra, edges with two equivalent Cu(2)U4Si4Ni4 cuboctahedra, faces with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(3)U4Cu4Si4 cuboctahedra. All Cu(1)-Cu(3) bond lengths are 2.79 Å. All Cu(1)-Si(2) bond lengths are 2.40 Å. In the second Cu site, Cu(2) is bonded to four equivalent U(1), four equivalent Ni(1), and four equivalent Si(1) atoms to form distorted CuU4Si4Ni4 cuboctahedra that share corners with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(2)U4Si4Ni4 cuboctahedra, corners with eight equivalent Cu(3)U4Cu4Si4 cuboctahedra, edges with two equivalent Cu(1)U4Cu4Si4 cuboctahedra, faces with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(2)U4Si4Ni4 cuboctahedra. All Cu(2)-Si(1) bond lengths are 2.34 Å. In the third Cu site, Cu(3) is bonded to four equivalent U(1), four equivalent Cu(1), and four equivalent Si(2) atoms to form distorted CuU4Cu4Si4 cuboctahedra that share corners with four equivalent Ni(1)U4Cu4Si4 cuboctahedra, corners with four equivalent Cu(3)U4Cu4Si4 cuboctahedra, corners with eight equivalent Cu(2)U4Si4Ni4 cuboctahedra, edges with two equivalent Ni(1)U4Cu4Si4 cuboctahedra, faces with four equivalent Cu(1)U4Cu4Si4 cuboctahedra, and faces with four equivalent Cu(3)U4Cu4Si4 cuboctahedra. All Cu(3)-Si(2) bond lengths are 2.40 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent U(1), two equivalent Ni(1), two equivalent Cu(2), and one Si(2) atom. The Si(1)-Si(2) bond length is 2.34 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent U(1), two equivalent Cu(1), two equivalent Cu(3), and one Si(1) atom.