Al8Cr5 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the trigonal R3m space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 12-coordinate geometry to three equivalent Cr(2), three equivalent Cr(3), three equivalent Cr(4), and three equivalent Al(3) atoms. In the second Cr site, Cr(2) is bonded in a 12-coordinate geometry to one Cr(1), one Cr(4), two equivalent Cr(2), two equivalent Cr(3), one Al(1), one Al(4), two equivalent Al(2), and two equivalent Al(5) atoms. In the third Cr site, Cr(3) is bonded in a 12-coordinate geometry to one Cr(1), two equivalent Cr(2), two equivalent Cr(4), one Al(2), one Al(3), one Al(4), and four equivalent Al(5) atoms. In the fourth Cr site, Cr(4) is bonded in a 12-coordinate geometry to one Cr(1), one Cr(2), two equivalent Cr(3), one Al(2), one Al(4), two equivalent Al(3), and four equivalent Al(5) atoms. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded in a distorted cuboctahedral geometry to three equivalent Cr(2), three equivalent Al(2), three equivalent Al(3), and three equivalent Al(4) atoms. In the second Al site, Al(2) is bonded in a 13-coordinate geometry to one Cr(3), one Cr(4), two equivalent Cr(2), one Al(1), one Al(3), three equivalent Al(4), and four equivalent Al(5) atoms. In the third Al site, Al(3) is bonded in a 12-coordinate geometry to one Cr(1), one Cr(3), two equivalent Cr(4), one Al(1), one Al(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Al(5) atoms. In the fourth Al site, Al(4) is bonded in a 11-coordinate geometry to one Cr(2), one Cr(3), one Cr(4), one Al(1), two equivalent Al(3), two equivalent Al(5), and three equivalent Al(2) atoms. In the fifth Al site, Al(5) is bonded in a 11-coordinate geometry to one Cr(2), two equivalent Cr(3), two equivalent Cr(4), one Al(3), one Al(4), two equivalent Al(2), and two equivalent Al(5) atoms.
Al8Cr5 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the trigonal R3m space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 12-coordinate geometry to three equivalent Cr(2), three equivalent Cr(3), three equivalent Cr(4), and three equivalent Al(3) atoms. All Cr(1)-Cr(2) bond lengths are 2.30 Å. All Cr(1)-Cr(3) bond lengths are 2.60 Å. All Cr(1)-Cr(4) bond lengths are 2.71 Å. All Cr(1)-Al(3) bond lengths are 2.61 Å. In the second Cr site, Cr(2) is bonded in a 12-coordinate geometry to one Cr(1), one Cr(4), two equivalent Cr(2), two equivalent Cr(3), one Al(1), one Al(4), two equivalent Al(2), and two equivalent Al(5) atoms. The Cr(2)-Cr(4) bond length is 2.58 Å. Both Cr(2)-Cr(2) bond lengths are 2.81 Å. Both Cr(2)-Cr(3) bond lengths are 2.58 Å. The Cr(2)-Al(1) bond length is 2.51 Å. The Cr(2)-Al(4) bond length is 2.72 Å. Both Cr(2)-Al(2) bond lengths are 2.69 Å. Both Cr(2)-Al(5) bond lengths are 2.60 Å. In the third Cr site, Cr(3) is bonded in a 12-coordinate geometry to one Cr(1), two equivalent Cr(2), two equivalent Cr(4), one Al(2), one Al(3), one Al(4), and four equivalent Al(5) atoms. Both Cr(3)-Cr(4) bond lengths are 2.82 Å. The Cr(3)-Al(2) bond length is 2.63 Å. The Cr(3)-Al(3) bond length is 2.57 Å. The Cr(3)-Al(4) bond length is 2.55 Å. There are two shorter (2.61 Å) and two longer (2.64 Å) Cr(3)-Al(5) bond lengths. In the fourth Cr site, Cr(4) is bonded in a 12-coordinate geometry to one Cr(1), one Cr(2), two equivalent Cr(3), one Al(2), one Al(4), two equivalent Al(3), and four equivalent Al(5) atoms. The Cr(4)-Al(2) bond length is 2.62 Å. The Cr(4)-Al(4) bond length is 2.88 Å. Both Cr(4)-Al(3) bond lengths are 2.60 Å. There are two shorter (2.64 Å) and two longer (2.74 Å) Cr(4)-Al(5) bond lengths. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded in a distorted cuboctahedral geometry to three equivalent Cr(2), three equivalent Al(2), three equivalent Al(3), and three equivalent Al(4) atoms. All Al(1)-Al(2) bond lengths are 2.70 Å. All Al(1)-Al(3) bond lengths are 2.77 Å. All Al(1)-Al(4) bond lengths are 2.68 Å. In the second Al site, Al(2) is bonded in a 13-coordinate geometry to one Cr(3), one Cr(4), two equivalent Cr(2), one Al(1), one Al(3), three equivalent Al(4), and four equivalent Al(5) atoms. The Al(2)-Al(3) bond length is 2.94 Å. There is one shorter (2.62 Å) and two longer (2.87 Å) Al(2)-Al(4) bond lengths. All Al(2)-Al(5) bond lengths are 3.04 Å. In the third Al site, Al(3) is bonded in a 12-coordinate geometry to one Cr(1), one Cr(3), two equivalent Cr(4), one Al(1), one Al(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Al(5) atoms. Both Al(3)-Al(3) bond lengths are 2.86 Å. Both Al(3)-Al(4) bond lengths are 2.80 Å. Both Al(3)-Al(5) bond lengths are 2.71 Å. In the fourth Al site, Al(4) is bonded in a 11-coordinate geometry to one Cr(2), one Cr(3), one Cr(4), one Al(1), two equivalent Al(3), two equivalent Al(5), and three equivalent Al(2) atoms. Both Al(4)-Al(5) bond lengths are 2.92 Å. In the fifth Al site, Al(5) is bonded in a 11-coordinate geometry to one Cr(2), two equivalent Cr(3), two equivalent Cr(4), one Al(3), one Al(4), two equivalent Al(2), and two equivalent Al(5) atoms. Both Al(5)-Al(5) bond lengths are 2.79 Å.