Th2Au3Al4Si2 crystallizes in the orthorhombic Cmmm space group. Th(1) is bonded in a 14-coordinate geometry to four equivalent Au(1), two equivalent Al(1), two equivalent Al(2), and six equivalent Si(1) atoms. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Al(1), two equivalent Al(2), and one Si(1) atom. In the second Au site, Au(2) is bonded in a body-centered cubic geometry to four equivalent Al(1) and four equivalent Al(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Th(1), two equivalent Au(1), and two equivalent Au(2) atoms to form a mixture of corner, edge, and face-sharing AlTh2Au4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent Th(1), two equivalent Au(1), and two equivalent Au(2) atoms to form a mixture of corner, edge, and face-sharing AlTh2Au4 tetrahedra. Si(1) is bonded in a distorted single-bond geometry to six equivalent Th(1) and one Au(1) atom.
Th2Au3Al4Si2 crystallizes in the orthorhombic Cmmm space group. Th(1) is bonded in a 14-coordinate geometry to four equivalent Au(1), two equivalent Al(1), two equivalent Al(2), and six equivalent Si(1) atoms. All Th(1)-Au(1) bond lengths are 3.32 Å. Both Th(1)-Al(1) bond lengths are 3.49 Å. Both Th(1)-Al(2) bond lengths are 3.48 Å. There are two shorter (3.11 Å) and four longer (3.25 Å) Th(1)-Si(1) bond lengths. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Al(1), two equivalent Al(2), and one Si(1) atom. Both Au(1)-Al(1) bond lengths are 2.57 Å. Both Au(1)-Al(2) bond lengths are 2.59 Å. The Au(1)-Si(1) bond length is 2.46 Å. In the second Au site, Au(2) is bonded in a body-centered cubic geometry to four equivalent Al(1) and four equivalent Al(2) atoms. All Au(2)-Al(1) bond lengths are 2.63 Å. All Au(2)-Al(2) bond lengths are 2.61 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Th(1), two equivalent Au(1), and two equivalent Au(2) atoms to form a mixture of corner, edge, and face-sharing AlTh2Au4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent Th(1), two equivalent Au(1), and two equivalent Au(2) atoms to form a mixture of corner, edge, and face-sharing AlTh2Au4 tetrahedra. Si(1) is bonded in a distorted single-bond geometry to six equivalent Th(1) and one Au(1) atom.