Eu2Au2Al6Si3 crystallizes in the tetragonal I4mm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 16-coordinate geometry to four equivalent Au(2), four equivalent Al(1), four equivalent Al(3), and four equivalent Si(2) atoms. In the second Eu site, Eu(2) is bonded in a 16-coordinate geometry to four equivalent Al(2), four equivalent Al(3), four equivalent Si(1), and four equivalent Si(3) atoms. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a body-centered cubic geometry to four equivalent Al(1) and four equivalent Al(2) atoms. In the second Au site, Au(2) is bonded in a 5-coordinate geometry to four equivalent Eu(1), four equivalent Al(1), and one Si(2) atom. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Eu(1), two equivalent Au(1), and two equivalent Au(2) atoms to form distorted AlEu2Au4 tetrahedra that share corners with two equivalent Al(1)Eu2Au4 tetrahedra, corners with six equivalent Al(2)Eu2Si2Au2 tetrahedra, corners with six equivalent Al(3)Eu4Si4 tetrahedra,  an edgeedge with one Al(2)Eu2Si2Au2 tetrahedra,  an edgeedge with one Al(3)Eu4Si4 tetrahedra, edges with two equivalent Al(1)Eu2Au4 tetrahedra, and faces with four equivalent Al(1)Eu2Au4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent Eu(2), two equivalent Au(1), and two equivalent Si(1) atoms to form distorted AlEu2Si2Au2 tetrahedra that share corners with two equivalent Al(2)Eu2Si2Au2 tetrahedra, corners with six equivalent Al(1)Eu2Au4 tetrahedra, corners with six equivalent Al(3)Eu4Si4 tetrahedra,  an edgeedge with one Al(1)Eu2Au4 tetrahedra,  an edgeedge with one Al(3)Eu4Si4 tetrahedra, edges with two equivalent Al(2)Eu2Si2Au2 tetrahedra, and faces with four equivalent Al(2)Eu2Si2Au2 tetrahedra. In the third Al site, Al(3) is bonded to two equivalent Eu(1), two equivalent Eu(2), two equivalent Si(2), and two equivalent Si(3) atoms to form distorted AlEu4Si4 tetrahedra that share corners with six equivalent Al(1)Eu2Au4 tetrahedra, corners with six equivalent Al(2)Eu2Si2Au2 tetrahedra,  an edgeedge with one Al(1)Eu2Au4 tetrahedra,  an edgeedge with one Al(2)Eu2Si2Au2 tetrahedra, edges with four equivalent Al(3)Eu4Si4 tetrahedra, and faces with four equivalent Al(3)Eu4Si4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Eu(2), four equivalent Al(2), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 5-coordinate geometry to four equivalent Eu(1), one Au(2), and four equivalent Al(3) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to four equivalent Eu(2), four equivalent Al(3), and one Si(1) atom.
Eu2Au2Al6Si3 crystallizes in the tetragonal I4mm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 16-coordinate geometry to four equivalent Au(2), four equivalent Al(1), four equivalent Al(3), and four equivalent Si(2) atoms. All Eu(1)-Au(2) bond lengths are 3.35 Å. All Eu(1)-Al(1) bond lengths are 3.40 Å. All Eu(1)-Al(3) bond lengths are 3.43 Å. All Eu(1)-Si(2) bond lengths are 3.37 Å. In the second Eu site, Eu(2) is bonded in a 16-coordinate geometry to four equivalent Al(2), four equivalent Al(3), four equivalent Si(1), and four equivalent Si(3) atoms. All Eu(2)-Al(2) bond lengths are 3.29 Å. All Eu(2)-Al(3) bond lengths are 3.44 Å. All Eu(2)-Si(1) bond lengths are 3.31 Å. All Eu(2)-Si(3) bond lengths are 3.38 Å. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a body-centered cubic geometry to four equivalent Al(1) and four equivalent Al(2) atoms. All Au(1)-Al(1) bond lengths are 2.66 Å. All Au(1)-Al(2) bond lengths are 2.61 Å. In the second Au site, Au(2) is bonded in a 5-coordinate geometry to four equivalent Eu(1), four equivalent Al(1), and one Si(2) atom. All Au(2)-Al(1) bond lengths are 2.59 Å. The Au(2)-Si(2) bond length is 2.51 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Eu(1), two equivalent Au(1), and two equivalent Au(2) atoms to form distorted AlEu2Au4 tetrahedra that share corners with two equivalent Al(1)Eu2Au4 tetrahedra, corners with six equivalent Al(2)Eu2Si2Au2 tetrahedra, corners with six equivalent Al(3)Eu4Si4 tetrahedra,  an edgeedge with one Al(2)Eu2Si2Au2 tetrahedra,  an edgeedge with one Al(3)Eu4Si4 tetrahedra, edges with two equivalent Al(1)Eu2Au4 tetrahedra, and faces with four equivalent Al(1)Eu2Au4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent Eu(2), two equivalent Au(1), and two equivalent Si(1) atoms to form distorted AlEu2Si2Au2 tetrahedra that share corners with two equivalent Al(2)Eu2Si2Au2 tetrahedra, corners with six equivalent Al(1)Eu2Au4 tetrahedra, corners with six equivalent Al(3)Eu4Si4 tetrahedra,  an edgeedge with one Al(1)Eu2Au4 tetrahedra,  an edgeedge with one Al(3)Eu4Si4 tetrahedra, edges with two equivalent Al(2)Eu2Si2Au2 tetrahedra, and faces with four equivalent Al(2)Eu2Si2Au2 tetrahedra. Both Al(2)-Si(1) bond lengths are 2.58 Å. In the third Al site, Al(3) is bonded to two equivalent Eu(1), two equivalent Eu(2), two equivalent Si(2), and two equivalent Si(3) atoms to form distorted AlEu4Si4 tetrahedra that share corners with six equivalent Al(1)Eu2Au4 tetrahedra, corners with six equivalent Al(2)Eu2Si2Au2 tetrahedra,  an edgeedge with one Al(1)Eu2Au4 tetrahedra,  an edgeedge with one Al(2)Eu2Si2Au2 tetrahedra, edges with four equivalent Al(3)Eu4Si4 tetrahedra, and faces with four equivalent Al(3)Eu4Si4 tetrahedra. Both Al(3)-Si(2) bond lengths are 2.58 Å. Both Al(3)-Si(3) bond lengths are 2.58 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Eu(2), four equivalent Al(2), and one Si(3) atom. The Si(1)-Si(3) bond length is 2.42 Å. In the second Si site, Si(2) is bonded in a 5-coordinate geometry to four equivalent Eu(1), one Au(2), and four equivalent Al(3) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to four equivalent Eu(2), four equivalent Al(3), and one Si(1) atom.