U3Co2Si7 crystallizes in the orthorhombic Cmmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to four equivalent Co(1), two equivalent Si(2), two equivalent Si(3), and six equivalent Si(4) atoms. In the second U site, U(2) is bonded to four equivalent Si(1), four equivalent Si(2), and four equivalent Si(3) atoms to form a mixture of distorted corner and face-sharing USi12 cuboctahedra. Co(1) is bonded in a 5-coordinate geometry to four equivalent U(1), one Si(4), two equivalent Si(2), and two equivalent Si(3) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a square co-planar geometry to four equivalent U(2) and four equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 12-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Co(1), two equivalent Si(1), and four equivalent Si(3) atoms. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Co(1), and four equivalent Si(2) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to six equivalent U(1), one Co(1), and two equivalent Si(4) atoms.
U3Co2Si7 crystallizes in the orthorhombic Cmmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to four equivalent Co(1), two equivalent Si(2), two equivalent Si(3), and six equivalent Si(4) atoms. All U(1)-Co(1) bond lengths are 3.15 Å. Both U(1)-Si(2) bond lengths are 3.14 Å. Both U(1)-Si(3) bond lengths are 3.11 Å. There are four shorter (2.96 Å) and two longer (3.01 Å) U(1)-Si(4) bond lengths. In the second U site, U(2) is bonded to four equivalent Si(1), four equivalent Si(2), and four equivalent Si(3) atoms to form a mixture of distorted corner and face-sharing USi12 cuboctahedra. All U(2)-Si(1) bond lengths are 2.83 Å. All U(2)-Si(2) bond lengths are 2.90 Å. All U(2)-Si(3) bond lengths are 2.93 Å. Co(1) is bonded in a 5-coordinate geometry to four equivalent U(1), one Si(4), two equivalent Si(2), and two equivalent Si(3) atoms. The Co(1)-Si(4) bond length is 2.28 Å. Both Co(1)-Si(2) bond lengths are 2.23 Å. Both Co(1)-Si(3) bond lengths are 2.25 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a square co-planar geometry to four equivalent U(2) and four equivalent Si(2) atoms. All Si(1)-Si(2) bond lengths are 2.92 Å. In the second Si site, Si(2) is bonded in a 12-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Co(1), two equivalent Si(1), and four equivalent Si(3) atoms. All Si(2)-Si(3) bond lengths are 2.83 Å. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Co(1), and four equivalent Si(2) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to six equivalent U(1), one Co(1), and two equivalent Si(4) atoms. Both Si(4)-Si(4) bond lengths are 2.40 Å.