Cr4Al8Si3 crystallizes in the triclinic P-1 space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 10-coordinate geometry to one Al(1), one Al(2), one Al(3), three equivalent Al(4), one Si(1), and three equivalent Si(2) atoms. In the second Cr site, Cr(2) is bonded in a 10-coordinate geometry to one Al(4), two equivalent Al(1), three equivalent Al(2), three equivalent Al(3), and one Si(2) atom. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded in a 8-coordinate geometry to one Cr(1), two equivalent Cr(2), two equivalent Al(2), two equivalent Al(3), and one Si(1) atom. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to one Cr(1), three equivalent Cr(2), one Al(2), one Al(3), one Al(4), two equivalent Al(1), and one Si(2) atom. In the third Al site, Al(3) is bonded in a 5-coordinate geometry to one Cr(1), three equivalent Cr(2), one Al(2), one Al(4), two equivalent Al(1), and one Si(2) atom. In the fourth Al site, Al(4) is bonded in a 11-coordinate geometry to one Cr(2), three equivalent Cr(1), one Al(2), one Al(3), one Al(4), 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 2-coordinate geometry to two equivalent Cr(1), two equivalent Al(1), and four equivalent Al(4) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Cr(2), three equivalent Cr(1), one Al(2), one Al(3), two equivalent Al(4), and one Si(2) atom.
Cr4Al8Si3 crystallizes in the triclinic P-1 space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 10-coordinate geometry to one Al(1), one Al(2), one Al(3), three equivalent Al(4), one Si(1), and three equivalent Si(2) atoms. The Cr(1)-Al(1) bond length is 2.55 Å. The Cr(1)-Al(2) bond length is 2.66 Å. The Cr(1)-Al(3) bond length is 2.55 Å. There are a spread of Cr(1)-Al(4) bond distances ranging from 2.58-2.78 Å. The Cr(1)-Si(1) bond length is 2.27 Å. There are a spread of Cr(1)-Si(2) bond distances ranging from 2.50-2.67 Å. In the second Cr site, Cr(2) is bonded in a 10-coordinate geometry to one Al(4), two equivalent Al(1), three equivalent Al(2), three equivalent Al(3), and one Si(2) atom. The Cr(2)-Al(4) bond length is 2.70 Å. There is one shorter (2.41 Å) and one longer (2.79 Å) Cr(2)-Al(1) bond length. There are a spread of Cr(2)-Al(2) bond distances ranging from 2.55-2.74 Å. There is one shorter (2.54 Å) and two longer (2.55 Å) Cr(2)-Al(3) bond lengths. The Cr(2)-Si(2) bond length is 2.67 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded in a 8-coordinate geometry to one Cr(1), two equivalent Cr(2), two equivalent Al(2), two equivalent Al(3), and one Si(1) atom. There is one shorter (2.56 Å) and one longer (2.65 Å) Al(1)-Al(2) bond length. There is one shorter (2.65 Å) and one longer (2.67 Å) Al(1)-Al(3) bond length. The Al(1)-Si(1) bond length is 2.71 Å. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to one Cr(1), three equivalent Cr(2), one Al(2), one Al(3), one Al(4), two equivalent Al(1), and one Si(2) atom. The Al(2)-Al(2) bond length is 2.59 Å. The Al(2)-Al(3) bond length is 2.69 Å. The Al(2)-Al(4) bond length is 2.61 Å. The Al(2)-Si(2) bond length is 2.92 Å. In the third Al site, Al(3) is bonded in a 5-coordinate geometry to one Cr(1), three equivalent Cr(2), one Al(2), one Al(4), two equivalent Al(1), and one Si(2) atom. The Al(3)-Al(4) bond length is 2.88 Å. The Al(3)-Si(2) bond length is 2.51 Å. In the fourth Al site, Al(4) is bonded in a 11-coordinate geometry to one Cr(2), three equivalent Cr(1), one Al(2), one Al(3), one Al(4), two equivalent Si(1), and two equivalent Si(2) atoms. The Al(4)-Al(4) bond length is 2.73 Å. There is one shorter (2.76 Å) and one longer (2.88 Å) Al(4)-Si(1) bond length. There is one shorter (2.75 Å) and one longer (2.92 Å) Al(4)-Si(2) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 2-coordinate geometry to two equivalent Cr(1), two equivalent Al(1), and four equivalent Al(4) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Cr(2), three equivalent Cr(1), one Al(2), one Al(3), two equivalent Al(4), and one Si(2) atom. The Si(2)-Si(2) bond length is 2.74 Å.