U2CoSi3 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 Co(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form UCo2Si10 cuboctahedra that share edges with four equivalent U(1)Co2Si10 cuboctahedra, edges with eight equivalent U(2)Co4Si8 cuboctahedra, faces with four equivalent U(1)Co2Si10 cuboctahedra, and faces with four equivalent U(2)Co4Si8 cuboctahedra. In the second U site, U(2) is bonded to four equivalent Co(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form UCo4Si8 cuboctahedra that share edges with four equivalent U(2)Co4Si8 cuboctahedra, edges with eight equivalent U(1)Co2Si10 cuboctahedra, faces with four equivalent U(1)Co2Si10 cuboctahedra, and faces with four equivalent U(2)Co4Si8 cuboctahedra. Co(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 Co(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 Co(1), and two equivalent Si(1) atoms.
U2CoSi3 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 Co(1), two equivalent Si(3), four equivalent Si(1), and four equivalent Si(2) atoms to form UCo2Si10 cuboctahedra that share edges with four equivalent U(1)Co2Si10 cuboctahedra, edges with eight equivalent U(2)Co4Si8 cuboctahedra, faces with four equivalent U(1)Co2Si10 cuboctahedra, and faces with four equivalent U(2)Co4Si8 cuboctahedra. Both U(1)-Co(1) bond lengths are 2.89 Å. Both U(1)-Si(3) bond lengths are 3.04 Å. All U(1)-Si(1) bond lengths are 3.00 Å. All U(1)-Si(2) bond lengths are 2.96 Å. In the second U site, U(2) is bonded to four equivalent Co(1), two equivalent Si(1), two equivalent Si(2), and four equivalent Si(3) atoms to form UCo4Si8 cuboctahedra that share edges with four equivalent U(2)Co4Si8 cuboctahedra, edges with eight equivalent U(1)Co2Si10 cuboctahedra, faces with four equivalent U(1)Co2Si10 cuboctahedra, and faces with four equivalent U(2)Co4Si8 cuboctahedra. All U(2)-Co(1) bond lengths are 2.97 Å. Both U(2)-Si(1) bond lengths are 3.00 Å. Both U(2)-Si(2) bond lengths are 2.89 Å. All U(2)-Si(3) bond lengths are 2.98 Å. Co(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 Co(1)-Si(3) bond length is 2.29 Å. Both Co(1)-Si(2) bond lengths are 2.29 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 2.34 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 Co(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 Co(1), and two equivalent Si(1) atoms.