UFe5Co5Si2 crystallizes in the monoclinic Cm space group. U(1) is bonded in a 20-coordinate geometry to two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), four equivalent Fe(1), one Co(1), one Co(2), one Co(3), one Co(4), two equivalent Co(5), and four equivalent Si(1) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent U(1), one Fe(2), one Fe(3), one Fe(4), two equivalent Fe(1), one Co(1), one Co(2), one Co(3), one Co(4), and one Co(5) atom to form distorted FeU2Fe5Co5 cuboctahedra that share corners with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, corners with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, corners with six equivalent Fe(1)U2Fe5Co5 cuboctahedra,  an edgeedge with one Fe(3)U2Fe3Co5Si2 cuboctahedra, edges with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, faces with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, faces with two equivalent Fe(1)U2Fe5Co5 cuboctahedra, and faces with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(4), two equivalent Fe(1), one Co(3), one Co(4), one Co(5), two equivalent Co(2), and two equivalent Si(1) atoms. In the third Fe site, Fe(3) is bonded to two equivalent U(1), one Fe(4), two equivalent Fe(1), one Co(3), one Co(4), one Co(5), two equivalent Co(1), and two equivalent Si(1) atoms to form distorted FeU2Fe3Co5Si2 cuboctahedra that share corners with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, corners with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, edges with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, edges with two equivalent Fe(1)U2Fe5Co5 cuboctahedra, edges with two equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, faces with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, and faces with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra. In the fourth Fe site, Fe(4) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(2), one Fe(3), two equivalent Fe(1), one Co(1), one Co(2), two equivalent Co(4), and two equivalent Si(1) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded in a 10-coordinate geometry to one U(1), one Fe(4), two equivalent Fe(1), two equivalent Fe(3), one Co(2), one Co(5), and two equivalent Si(1) atoms. In the second Co site, Co(2) is bonded in a 10-coordinate geometry to one U(1), one Fe(4), two equivalent Fe(1), two equivalent Fe(2), one Co(1), one Co(5), and two equivalent Si(1) atoms. In the third Co site, Co(3) is bonded in a 10-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), one Co(4), two equivalent Co(5), and two equivalent Si(1) atoms. In the fourth Co site, Co(4) is bonded in a 10-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), two equivalent Fe(4), one Co(3), and two equivalent Si(1) atoms. In the fifth Co site, Co(5) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(2), one Fe(3), two equivalent Fe(1), one Co(1), one Co(2), two equivalent Co(3), and two equivalent Si(1) atoms. Si(1) is bonded to two equivalent U(1), one Fe(2), one Fe(3), one Fe(4), one Co(1), one Co(2), one Co(3), one Co(4), one Co(5), and two equivalent Si(1) atoms to form distorted SiU2Fe3Co5Si2 cuboctahedra that share corners with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, corners with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, corners with six equivalent Si(1)U2Fe3Co5Si2 cuboctahedra,  an edgeedge with one Fe(3)U2Fe3Co5Si2 cuboctahedra, edges with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, faces with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, faces with two equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, and faces with four equivalent Fe(1)U2Fe5Co5 cuboctahedra.
UFe5Co5Si2 crystallizes in the monoclinic Cm space group. U(1) is bonded in a 20-coordinate geometry to two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), four equivalent Fe(1), one Co(1), one Co(2), one Co(3), one Co(4), two equivalent Co(5), and four equivalent Si(1) atoms. Both U(1)-Fe(2) bond lengths are 3.00 Å. Both U(1)-Fe(3) bond lengths are 3.00 Å. Both U(1)-Fe(4) bond lengths are 3.02 Å. There are two shorter (3.09 Å) and two longer (3.12 Å) U(1)-Fe(1) bond lengths. The U(1)-Co(1) bond length is 2.78 Å. The U(1)-Co(2) bond length is 2.77 Å. The U(1)-Co(3) bond length is 2.81 Å. The U(1)-Co(4) bond length is 2.81 Å. Both U(1)-Co(5) bond lengths are 3.04 Å. There are two shorter (3.10 Å) and two longer (3.11 Å) U(1)-Si(1) bond lengths. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent U(1), one Fe(2), one Fe(3), one Fe(4), two equivalent Fe(1), one Co(1), one Co(2), one Co(3), one Co(4), and one Co(5) atom to form distorted FeU2Fe5Co5 cuboctahedra that share corners with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, corners with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, corners with six equivalent Fe(1)U2Fe5Co5 cuboctahedra,  an edgeedge with one Fe(3)U2Fe3Co5Si2 cuboctahedra, edges with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, faces with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, faces with two equivalent Fe(1)U2Fe5Co5 cuboctahedra, and faces with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra. The Fe(1)-Fe(2) bond length is 2.38 Å. The Fe(1)-Fe(3) bond length is 2.36 Å. The Fe(1)-Fe(4) bond length is 2.39 Å. There is one shorter (2.40 Å) and one longer (2.42 Å) Fe(1)-Fe(1) bond length. The Fe(1)-Co(1) bond length is 2.50 Å. The Fe(1)-Co(2) bond length is 2.50 Å. The Fe(1)-Co(3) bond length is 2.48 Å. The Fe(1)-Co(4) bond length is 2.52 Å. The Fe(1)-Co(5) bond length is 2.35 Å. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(4), two equivalent Fe(1), one Co(3), one Co(4), one Co(5), two equivalent Co(2), and two equivalent Si(1) atoms. The Fe(2)-Fe(4) bond length is 2.54 Å. The Fe(2)-Co(3) bond length is 2.54 Å. The Fe(2)-Co(4) bond length is 2.60 Å. The Fe(2)-Co(5) bond length is 2.59 Å. Both Fe(2)-Co(2) bond lengths are 2.61 Å. Both Fe(2)-Si(1) bond lengths are 2.37 Å. In the third Fe site, Fe(3) is bonded to two equivalent U(1), one Fe(4), two equivalent Fe(1), one Co(3), one Co(4), one Co(5), two equivalent Co(1), and two equivalent Si(1) atoms to form distorted FeU2Fe3Co5Si2 cuboctahedra that share corners with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, corners with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, edges with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, edges with two equivalent Fe(1)U2Fe5Co5 cuboctahedra, edges with two equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, faces with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, and faces with four equivalent Si(1)U2Fe3Co5Si2 cuboctahedra. The Fe(3)-Fe(4) bond length is 2.54 Å. The Fe(3)-Co(3) bond length is 2.60 Å. The Fe(3)-Co(4) bond length is 2.55 Å. The Fe(3)-Co(5) bond length is 2.56 Å. Both Fe(3)-Co(1) bond lengths are 2.61 Å. Both Fe(3)-Si(1) bond lengths are 2.38 Å. In the fourth Fe site, Fe(4) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(2), one Fe(3), two equivalent Fe(1), one Co(1), one Co(2), two equivalent Co(4), and two equivalent Si(1) atoms. The Fe(4)-Co(1) bond length is 2.53 Å. The Fe(4)-Co(2) bond length is 2.58 Å. Both Fe(4)-Co(4) bond lengths are 2.61 Å. Both Fe(4)-Si(1) bond lengths are 2.37 Å. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded in a 10-coordinate geometry to one U(1), one Fe(4), two equivalent Fe(1), two equivalent Fe(3), one Co(2), one Co(5), and two equivalent Si(1) atoms. The Co(1)-Co(2) bond length is 2.51 Å. The Co(1)-Co(5) bond length is 2.58 Å. Both Co(1)-Si(1) bond lengths are 2.46 Å. In the second Co site, Co(2) is bonded in a 10-coordinate geometry to one U(1), one Fe(4), two equivalent Fe(1), two equivalent Fe(2), one Co(1), one Co(5), and two equivalent Si(1) atoms. The Co(2)-Co(5) bond length is 2.53 Å. Both Co(2)-Si(1) bond lengths are 2.47 Å. In the third Co site, Co(3) is bonded in a 10-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), one Co(4), two equivalent Co(5), and two equivalent Si(1) atoms. The Co(3)-Co(4) bond length is 2.50 Å. Both Co(3)-Co(5) bond lengths are 2.60 Å. Both Co(3)-Si(1) bond lengths are 2.44 Å. In the fourth Co site, Co(4) is bonded in a 10-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), two equivalent Fe(4), one Co(3), and two equivalent Si(1) atoms. Both Co(4)-Si(1) bond lengths are 2.46 Å. In the fifth Co site, Co(5) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(2), one Fe(3), two equivalent Fe(1), one Co(1), one Co(2), two equivalent Co(3), and two equivalent Si(1) atoms. Both Co(5)-Si(1) bond lengths are 2.32 Å. Si(1) is bonded to two equivalent U(1), one Fe(2), one Fe(3), one Fe(4), one Co(1), one Co(2), one Co(3), one Co(4), one Co(5), and two equivalent Si(1) atoms to form distorted SiU2Fe3Co5Si2 cuboctahedra that share corners with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, corners with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, corners with six equivalent Si(1)U2Fe3Co5Si2 cuboctahedra,  an edgeedge with one Fe(3)U2Fe3Co5Si2 cuboctahedra, edges with four equivalent Fe(1)U2Fe5Co5 cuboctahedra, faces with two equivalent Fe(3)U2Fe3Co5Si2 cuboctahedra, faces with two equivalent Si(1)U2Fe3Co5Si2 cuboctahedra, and faces with four equivalent Fe(1)U2Fe5Co5 cuboctahedra. There is one shorter (2.41 Å) and one longer (2.42 Å) Si(1)-Si(1) bond length.