U2CuSi3 is hexagonal omega structure-derived structured and crystallizes in the orthorhombic Pmm2 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent Cu(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form UCu2Si10 cuboctahedra that share edges with four equivalent U(1)Cu2Si10 cuboctahedra, edges with eight equivalent U(2)Cu4Si8 cuboctahedra, faces with four equivalent U(1)Cu2Si10 cuboctahedra, and faces with four equivalent U(2)Cu4Si8 cuboctahedra. In the second U site, U(2) is bonded to four equivalent Cu(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form UCu4Si8 cuboctahedra that share edges with four equivalent U(2)Cu4Si8 cuboctahedra, edges with eight equivalent U(1)Cu2Si10 cuboctahedra, faces with four equivalent U(1)Cu2Si10 cuboctahedra, and faces with four equivalent U(2)Cu4Si8 cuboctahedra. Cu(1) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Si(3), and two equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), two equivalent Cu(1), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Cu(1), and two equivalent Si(1) atoms.
U2CuSi3 is hexagonal omega structure-derived structured and crystallizes in the orthorhombic Pmm2 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent Cu(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form UCu2Si10 cuboctahedra that share edges with four equivalent U(1)Cu2Si10 cuboctahedra, edges with eight equivalent U(2)Cu4Si8 cuboctahedra, faces with four equivalent U(1)Cu2Si10 cuboctahedra, and faces with four equivalent U(2)Cu4Si8 cuboctahedra. Both U(1)-Cu(1) bond lengths are 3.06 Å. Both U(1)-Si(3) bond lengths are 2.99 Å. All U(1)-Si(1) bond lengths are 3.00 Å. All U(1)-Si(2) bond lengths are 3.06 Å. In the second U site, U(2) is bonded to four equivalent Cu(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form UCu4Si8 cuboctahedra that share edges with four equivalent U(2)Cu4Si8 cuboctahedra, edges with eight equivalent U(1)Cu2Si10 cuboctahedra, faces with four equivalent U(1)Cu2Si10 cuboctahedra, and faces with four equivalent U(2)Cu4Si8 cuboctahedra. All U(2)-Cu(1) bond lengths are 3.07 Å. Both U(2)-Si(1) bond lengths are 2.98 Å. Both U(2)-Si(2) bond lengths are 3.07 Å. All U(2)-Si(3) bond lengths are 2.99 Å. Cu(1) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Si(3), and two equivalent Si(2) atoms. The Cu(1)-Si(3) bond length is 2.31 Å. Both Cu(1)-Si(2) bond lengths are 2.30 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), one Si(2), and two equivalent Si(3) atoms. The Si(1)-Si(2) bond length is 2.31 Å. Both Si(1)-Si(3) bond lengths are 2.34 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), two equivalent Cu(1), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Cu(1), and two equivalent Si(1) atoms.