UFe5Ni5Si2 crystallizes in the triclinic P-1 space group. U(1) is bonded in a 20-coordinate geometry to two equivalent Fe(3), four equivalent Fe(1), four equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(2), two equivalent Ni(3), two equivalent Ni(4), and two equivalent Si(1) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent U(1), one Fe(3), two equivalent Fe(2), one Ni(2), one Ni(3), one Ni(4), two equivalent Ni(1), and two equivalent Si(1) atoms to form distorted FeU2Fe3Si2Ni5 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with six equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra,  an edgeedge with one Fe(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(4)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(2)U2Fe6Si2Ni2 cuboctahedra, edges with three equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra,  a faceface with one Fe(1)U2Fe3Si2Ni5 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, and faces with six equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. In the second Fe site, Fe(2) is bonded to two equivalent U(1), one Fe(3), two equivalent Fe(1), one Ni(2), one Ni(3), one Ni(4), two equivalent Ni(1), and two equivalent Si(1) atoms to form distorted FeU2Fe3Si2Ni5 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with six equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra,  an edgeedge with one Fe(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(4)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(2)U2Fe6Si2Ni2 cuboctahedra, edges with three equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra,  a faceface with one Fe(2)U2Fe3Si2Ni5 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, and faces with six equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra. In the third Fe site, Fe(3) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(2), and two equivalent Si(1) atoms to form distorted FeU2Fe4Si2Ni4 cuboctahedra that share corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 10-coordinate geometry to one U(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(2), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom. In the second Ni site, Ni(2) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Ni(1), and two equivalent Si(1) atoms to form distorted NiU2Fe6Si2Ni2 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. In the third Ni site, Ni(3) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(4), and two equivalent Si(1) atoms to form distorted NiU2Fe4Si2Ni4 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(3), and two equivalent Si(1) atoms to form distorted NiU2Fe4Si2Ni4 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. Si(1) is bonded in a 10-coordinate geometry to one U(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(2), one Ni(2), one Ni(3), one Ni(4), and one Si(1) atom.
UFe5Ni5Si2 crystallizes in the triclinic P-1 space group. U(1) is bonded in a 20-coordinate geometry to two equivalent Fe(3), four equivalent Fe(1), four equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(2), two equivalent Ni(3), two equivalent Ni(4), and two equivalent Si(1) atoms. Both U(1)-Fe(3) bond lengths are 3.16 Å. There are two shorter (3.00 Å) and two longer (3.02 Å) U(1)-Fe(1) bond lengths. There are two shorter (3.04 Å) and two longer (3.06 Å) U(1)-Fe(2) bond lengths. Both U(1)-Ni(1) bond lengths are 2.74 Å. Both U(1)-Ni(2) bond lengths are 3.12 Å. Both U(1)-Ni(3) bond lengths are 3.15 Å. Both U(1)-Ni(4) bond lengths are 3.15 Å. Both U(1)-Si(1) bond lengths are 2.95 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent U(1), one Fe(3), two equivalent Fe(2), one Ni(2), one Ni(3), one Ni(4), two equivalent Ni(1), and two equivalent Si(1) atoms to form distorted FeU2Fe3Si2Ni5 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with six equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra,  an edgeedge with one Fe(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(4)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(2)U2Fe6Si2Ni2 cuboctahedra, edges with three equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra,  a faceface with one Fe(1)U2Fe3Si2Ni5 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, and faces with six equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. The Fe(1)-Fe(3) bond length is 2.40 Å. There is one shorter (2.57 Å) and one longer (2.59 Å) Fe(1)-Fe(2) bond length. The Fe(1)-Ni(2) bond length is 2.44 Å. The Fe(1)-Ni(3) bond length is 2.45 Å. The Fe(1)-Ni(4) bond length is 2.44 Å. There is one shorter (2.58 Å) and one longer (2.62 Å) Fe(1)-Ni(1) bond length. There is one shorter (2.54 Å) and one longer (2.55 Å) Fe(1)-Si(1) bond length. In the second Fe site, Fe(2) is bonded to two equivalent U(1), one Fe(3), two equivalent Fe(1), one Ni(2), one Ni(3), one Ni(4), two equivalent Ni(1), and two equivalent Si(1) atoms to form distorted FeU2Fe3Si2Ni5 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with six equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra,  an edgeedge with one Fe(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(3)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(4)U2Fe4Si2Ni4 cuboctahedra,  an edgeedge with one Ni(2)U2Fe6Si2Ni2 cuboctahedra, edges with three equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra,  a faceface with one Fe(2)U2Fe3Si2Ni5 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, and faces with six equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra. The Fe(2)-Fe(3) bond length is 2.33 Å. The Fe(2)-Ni(2) bond length is 2.37 Å. The Fe(2)-Ni(3) bond length is 2.36 Å. The Fe(2)-Ni(4) bond length is 2.37 Å. There is one shorter (2.64 Å) and one longer (2.68 Å) Fe(2)-Ni(1) bond length. There is one shorter (2.65 Å) and one longer (2.66 Å) Fe(2)-Si(1) bond length. In the third Fe site, Fe(3) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(2), and two equivalent Si(1) atoms to form distorted FeU2Fe4Si2Ni4 cuboctahedra that share corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. Both Fe(3)-Ni(1) bond lengths are 2.55 Å. Both Fe(3)-Ni(2) bond lengths are 2.42 Å. Both Fe(3)-Si(1) bond lengths are 2.52 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 10-coordinate geometry to one U(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(2), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom. The Ni(1)-Ni(1) bond length is 2.55 Å. The Ni(1)-Ni(2) bond length is 2.49 Å. The Ni(1)-Ni(3) bond length is 2.55 Å. The Ni(1)-Ni(4) bond length is 2.53 Å. In the second Ni site, Ni(2) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Ni(1), and two equivalent Si(1) atoms to form distorted NiU2Fe6Si2Ni2 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. Both Ni(2)-Si(1) bond lengths are 2.49 Å. In the third Ni site, Ni(3) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(4), and two equivalent Si(1) atoms to form distorted NiU2Fe4Si2Ni4 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. Both Ni(3)-Ni(4) bond lengths are 2.42 Å. Both Ni(3)-Si(1) bond lengths are 2.49 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent U(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ni(1), two equivalent Ni(3), and two equivalent Si(1) atoms to form distorted NiU2Fe4Si2Ni4 cuboctahedra that share corners with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, corners with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, corners with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, corners with four equivalent Ni(4)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra, edges with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, edges with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with two equivalent Fe(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(3)U2Fe4Si2Ni4 cuboctahedra, faces with two equivalent Ni(2)U2Fe6Si2Ni2 cuboctahedra, faces with four equivalent Fe(1)U2Fe3Si2Ni5 cuboctahedra, and faces with four equivalent Fe(2)U2Fe3Si2Ni5 cuboctahedra. Both Ni(4)-Si(1) bond lengths are 2.47 Å. Si(1) is bonded in a 10-coordinate geometry to one U(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(2), one Ni(2), one Ni(3), one Ni(4), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.48 Å.