U2PtSi3 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 Pt(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form USi10Pt2 cuboctahedra that share edges with four equivalent U(1)Si10Pt2 cuboctahedra, edges with eight equivalent U(2)Si8Pt4 cuboctahedra, faces with four equivalent U(1)Si10Pt2 cuboctahedra, and faces with four equivalent U(2)Si8Pt4 cuboctahedra. In the second U site, U(2) is bonded to four equivalent Pt(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form USi8Pt4 cuboctahedra that share edges with four equivalent U(2)Si8Pt4 cuboctahedra, edges with eight equivalent U(1)Si10Pt2 cuboctahedra, faces with four equivalent U(1)Si10Pt2 cuboctahedra, and faces with four equivalent U(2)Si8Pt4 cuboctahedra. Pt(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 9-coordinate geometry to two equivalent U(2), four equivalent U(1), two equivalent Pt(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 Pt(1), and two equivalent Si(1) atoms.
U2PtSi3 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 Pt(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form USi10Pt2 cuboctahedra that share edges with four equivalent U(1)Si10Pt2 cuboctahedra, edges with eight equivalent U(2)Si8Pt4 cuboctahedra, faces with four equivalent U(1)Si10Pt2 cuboctahedra, and faces with four equivalent U(2)Si8Pt4 cuboctahedra. Both U(1)-Pt(1) bond lengths are 3.12 Å. Both U(1)-Si(3) bond lengths are 3.03 Å. All U(1)-Si(1) bond lengths are 3.09 Å. All U(1)-Si(2) bond lengths are 3.13 Å. In the second U site, U(2) is bonded to four equivalent Pt(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form USi8Pt4 cuboctahedra that share edges with four equivalent U(2)Si8Pt4 cuboctahedra, edges with eight equivalent U(1)Si10Pt2 cuboctahedra, faces with four equivalent U(1)Si10Pt2 cuboctahedra, and faces with four equivalent U(2)Si8Pt4 cuboctahedra. All U(2)-Pt(1) bond lengths are 3.14 Å. Both U(2)-Si(1) bond lengths are 3.05 Å. Both U(2)-Si(2) bond lengths are 3.15 Å. All U(2)-Si(3) bond lengths are 3.10 Å. Pt(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 Pt(1)-Si(3) bond length is 2.39 Å. Both Pt(1)-Si(2) bond lengths are 2.39 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 2.33 Å. Both Si(1)-Si(3) bond lengths are 2.38 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 Pt(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 Pt(1), and two equivalent Si(1) atoms.