U2AuSi3 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 Au(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form USi10Au2 cuboctahedra that share edges with four equivalent U(1)Si10Au2 cuboctahedra, edges with eight equivalent U(2)Si8Au4 cuboctahedra, faces with four equivalent U(1)Si10Au2 cuboctahedra, and faces with four equivalent U(2)Si8Au4 cuboctahedra. In the second U site, U(2) is bonded to four equivalent Au(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form distorted USi8Au4 cuboctahedra that share edges with four equivalent U(2)Si8Au4 cuboctahedra, edges with eight equivalent U(1)Si10Au2 cuboctahedra, faces with four equivalent U(1)Si10Au2 cuboctahedra, and faces with four equivalent U(2)Si8Au4 cuboctahedra. Au(1) is bonded in a distorted trigonal planar 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 2-coordinate geometry to two equivalent U(2), four equivalent U(1), two equivalent Au(1), and one Si(1) atom. In the third Si site, Si(3) is bonded in a distorted single-bond geometry to two equivalent U(1), four equivalent U(2), one Au(1), and two equivalent Si(1) atoms.
U2AuSi3 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 Au(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form USi10Au2 cuboctahedra that share edges with four equivalent U(1)Si10Au2 cuboctahedra, edges with eight equivalent U(2)Si8Au4 cuboctahedra, faces with four equivalent U(1)Si10Au2 cuboctahedra, and faces with four equivalent U(2)Si8Au4 cuboctahedra. Both U(1)-Au(1) bond lengths are 3.19 Å. Both U(1)-Si(3) bond lengths are 2.94 Å. All U(1)-Si(1) bond lengths are 3.04 Å. All U(1)-Si(2) bond lengths are 3.10 Å. In the second U site, U(2) is bonded to four equivalent Au(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form distorted USi8Au4 cuboctahedra that share edges with four equivalent U(2)Si8Au4 cuboctahedra, edges with eight equivalent U(1)Si10Au2 cuboctahedra, faces with four equivalent U(1)Si10Au2 cuboctahedra, and faces with four equivalent U(2)Si8Au4 cuboctahedra. All U(2)-Au(1) bond lengths are 3.15 Å. Both U(2)-Si(1) bond lengths are 2.97 Å. Both U(2)-Si(2) bond lengths are 3.28 Å. All U(2)-Si(3) bond lengths are 3.05 Å. Au(1) is bonded in a distorted trigonal planar geometry to two equivalent U(1), four equivalent U(2), one Si(3), and two equivalent Si(2) atoms. The Au(1)-Si(3) bond length is 2.46 Å. Both Au(1)-Si(2) bond lengths are 2.45 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 2.32 Å. Both Si(1)-Si(3) bond lengths are 2.37 Å. In the second Si site, Si(2) is bonded in a 2-coordinate geometry to two equivalent U(2), four equivalent U(1), two equivalent Au(1), and one Si(1) atom. In the third Si site, Si(3) is bonded in a distorted single-bond geometry to two equivalent U(1), four equivalent U(2), one Au(1), and two equivalent Si(1) atoms.