U6Al8(FeSi)5 crystallizes in the orthorhombic Immm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 8-coordinate geometry to two equivalent Al(2), two equivalent Al(3), and four equivalent Si(1) atoms. In the second U site, U(2) is bonded in a distorted single-bond geometry to one Fe(1), one Al(2), one Al(3), two equivalent Al(1), two equivalent Al(4), one Si(2), and two equivalent Si(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(2) is bonded in a 8-coordinate geometry to four equivalent Al(2) and four equivalent Si(1) atoms. In the second Fe site, Fe(1) is bonded in a 1-coordinate geometry to one U(2), one Al(3), and one Si(1) atom. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to four equivalent U(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Si(2) atoms. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Fe(2), and four equivalent Si(1) atoms. In the third Al site, Al(3) is bonded in a 8-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Fe(1), and two equivalent Al(1) atoms. In the fourth Al site, Al(4) is bonded in a 10-coordinate geometry to four equivalent U(2), two equivalent Al(1), two equivalent Si(1), and two equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(1), two equivalent U(2), one Fe(1), one Fe(2), one Al(4), and two equivalent Al(2) atoms. In the second Si site, Si(2) is bonded to four equivalent U(2), four equivalent Al(1), and four equivalent Al(4) atoms to form face-sharing SiU4Al8 cuboctahedra.
U6Al8(FeSi)5 crystallizes in the orthorhombic Immm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 8-coordinate geometry to two equivalent Al(2), two equivalent Al(3), and four equivalent Si(1) atoms. Both U(1)-Al(2) bond lengths are 2.95 Å. Both U(1)-Al(3) bond lengths are 2.86 Å. All U(1)-Si(1) bond lengths are 2.91 Å. In the second U site, U(2) is bonded in a distorted single-bond geometry to one Fe(1), one Al(2), one Al(3), two equivalent Al(1), two equivalent Al(4), one Si(2), and two equivalent Si(1) atoms. The U(2)-Fe(1) bond length is 2.13 Å. The U(2)-Al(2) bond length is 3.00 Å. The U(2)-Al(3) bond length is 2.82 Å. Both U(2)-Al(1) bond lengths are 3.12 Å. Both U(2)-Al(4) bond lengths are 3.01 Å. The U(2)-Si(2) bond length is 3.12 Å. Both U(2)-Si(1) bond lengths are 2.97 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(2) is bonded in a 8-coordinate geometry to four equivalent Al(2) and four equivalent Si(1) atoms. All Fe(2)-Al(2) bond lengths are 2.71 Å. All Fe(2)-Si(1) bond lengths are 2.40 Å. In the second Fe site, Fe(1) is bonded in a 1-coordinate geometry to one U(2), one Al(3), and one Si(1) atom. The Fe(1)-Al(3) bond length is 2.47 Å. The Fe(1)-Si(1) bond length is 2.37 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to four equivalent U(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Si(2) atoms. Both Al(1)-Al(3) bond lengths are 2.79 Å. Both Al(1)-Al(4) bond lengths are 2.85 Å. Both Al(1)-Si(2) bond lengths are 2.89 Å. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Fe(2), and four equivalent Si(1) atoms. All Al(2)-Si(1) bond lengths are 2.64 Å. In the third Al site, Al(3) is bonded in a 8-coordinate geometry to two equivalent U(1), two equivalent U(2), two equivalent Fe(1), and two equivalent Al(1) atoms. In the fourth Al site, Al(4) is bonded in a 10-coordinate geometry to four equivalent U(2), two equivalent Al(1), two equivalent Si(1), and two equivalent Si(2) atoms. Both Al(4)-Si(1) bond lengths are 2.72 Å. Both Al(4)-Si(2) bond lengths are 2.96 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(1), two equivalent U(2), one Fe(1), one Fe(2), one Al(4), and two equivalent Al(2) atoms. In the second Si site, Si(2) is bonded to four equivalent U(2), four equivalent Al(1), and four equivalent Al(4) atoms to form face-sharing SiU4Al8 cuboctahedra.