Ta3Cr8Si is Hexagonal Laves-derived structured and crystallizes in the trigonal P3m1 space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 16-coordinate geometry to one Ta(2), three equivalent Cr(1), three equivalent Cr(3), six equivalent Cr(4), and three equivalent Si(1) atoms. In the second Ta site, Ta(2) is bonded in a 16-coordinate geometry to one Ta(1), three equivalent Ta(3), three equivalent Cr(2), three equivalent Cr(3), and six equivalent Cr(4) atoms. In the third Ta site, Ta(3) is bonded in a 16-coordinate geometry to three equivalent Ta(2), three equivalent Cr(2), three equivalent Cr(4), six equivalent Cr(3), and one Si(1) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to three equivalent Ta(1), three equivalent Cr(3), three equivalent Cr(4), and three equivalent Si(1) atoms to form CrTa3Cr6Si3 cuboctahedra that share corners with six equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, corners with six equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with six equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with two equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with nine equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, and faces with nine equivalent Cr(4)Ta5Cr6Si cuboctahedra. In the second Cr site, Cr(2) is bonded to three equivalent Ta(2), three equivalent Ta(3), three equivalent Cr(3), and three equivalent Cr(4) atoms to form CrTa6Cr6 cuboctahedra that share corners with six equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, corners with six equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with six equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with two equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with nine equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, and faces with nine equivalent Cr(4)Ta5Cr6Si cuboctahedra. In the third Cr site, Cr(3) is bonded to one Ta(1), one Ta(2), two equivalent Ta(3), one Cr(1), one Cr(2), four equivalent Cr(3), and two equivalent Si(1) atoms to form CrTa4Cr6Si2 cuboctahedra that share corners with two equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, corners with two equivalent Cr(2)Ta6Cr6 cuboctahedra, corners with four equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, corners with ten equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with two equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, edges with four equivalent Cr(4)Ta5Cr6Si cuboctahedra, faces with three equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with three equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with four equivalent Cr(4)Ta5Cr6Si cuboctahedra, and faces with eight equivalent Cr(3)Ta4Cr6Si2 cuboctahedra. In the fourth Cr site, Cr(4) is bonded to one Ta(3), two equivalent Ta(1), two equivalent Ta(2), one Cr(1), one Cr(2), four equivalent Cr(4), and one Si(1) atom to form CrTa5Cr6Si cuboctahedra that share corners with two equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, corners with two equivalent Cr(2)Ta6Cr6 cuboctahedra, corners with four equivalent Cr(4)Ta5Cr6Si cuboctahedra, corners with ten equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, edges with two equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with four equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, faces with three equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with three equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with four equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, and faces with eight equivalent Cr(4)Ta5Cr6Si cuboctahedra. Si(1) is bonded in a 16-coordinate geometry to one Ta(3), three equivalent Ta(1), three equivalent Cr(1), three equivalent Cr(4), and six equivalent Cr(3) atoms.
Ta3Cr8Si is Hexagonal Laves-derived structured and crystallizes in the trigonal P3m1 space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 16-coordinate geometry to one Ta(2), three equivalent Cr(1), three equivalent Cr(3), six equivalent Cr(4), and three equivalent Si(1) atoms. The Ta(1)-Ta(2) bond length is 3.05 Å. All Ta(1)-Cr(1) bond lengths are 2.83 Å. All Ta(1)-Cr(3) bond lengths are 2.78 Å. All Ta(1)-Cr(4) bond lengths are 2.86 Å. All Ta(1)-Si(1) bond lengths are 2.96 Å. In the second Ta site, Ta(2) is bonded in a 16-coordinate geometry to one Ta(1), three equivalent Ta(3), three equivalent Cr(2), three equivalent Cr(3), and six equivalent Cr(4) atoms. All Ta(2)-Ta(3) bond lengths are 2.97 Å. All Ta(2)-Cr(2) bond lengths are 2.84 Å. All Ta(2)-Cr(3) bond lengths are 2.85 Å. All Ta(2)-Cr(4) bond lengths are 2.87 Å. In the third Ta site, Ta(3) is bonded in a 16-coordinate geometry to three equivalent Ta(2), three equivalent Cr(2), three equivalent Cr(4), six equivalent Cr(3), and one Si(1) atom. All Ta(3)-Cr(2) bond lengths are 2.85 Å. All Ta(3)-Cr(4) bond lengths are 2.89 Å. All Ta(3)-Cr(3) bond lengths are 2.84 Å. The Ta(3)-Si(1) bond length is 2.94 Å. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to three equivalent Ta(1), three equivalent Cr(3), three equivalent Cr(4), and three equivalent Si(1) atoms to form CrTa3Cr6Si3 cuboctahedra that share corners with six equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, corners with six equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with six equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with two equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with nine equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, and faces with nine equivalent Cr(4)Ta5Cr6Si cuboctahedra. All Cr(1)-Cr(3) bond lengths are 2.42 Å. All Cr(1)-Cr(4) bond lengths are 2.44 Å. All Cr(1)-Si(1) bond lengths are 2.84 Å. In the second Cr site, Cr(2) is bonded to three equivalent Ta(2), three equivalent Ta(3), three equivalent Cr(3), and three equivalent Cr(4) atoms to form CrTa6Cr6 cuboctahedra that share corners with six equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, corners with six equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with six equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with two equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with nine equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, and faces with nine equivalent Cr(4)Ta5Cr6Si cuboctahedra. All Cr(2)-Cr(3) bond lengths are 2.47 Å. All Cr(2)-Cr(4) bond lengths are 2.47 Å. In the third Cr site, Cr(3) is bonded to one Ta(1), one Ta(2), two equivalent Ta(3), one Cr(1), one Cr(2), four equivalent Cr(3), and two equivalent Si(1) atoms to form CrTa4Cr6Si2 cuboctahedra that share corners with two equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, corners with two equivalent Cr(2)Ta6Cr6 cuboctahedra, corners with four equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, corners with ten equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with two equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, edges with four equivalent Cr(4)Ta5Cr6Si cuboctahedra, faces with three equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with three equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with four equivalent Cr(4)Ta5Cr6Si cuboctahedra, and faces with eight equivalent Cr(3)Ta4Cr6Si2 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.46 Å) Cr(3)-Cr(3) bond lengths. Both Cr(3)-Si(1) bond lengths are 2.83 Å. In the fourth Cr site, Cr(4) is bonded to one Ta(3), two equivalent Ta(1), two equivalent Ta(2), one Cr(1), one Cr(2), four equivalent Cr(4), and one Si(1) atom to form CrTa5Cr6Si cuboctahedra that share corners with two equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, corners with two equivalent Cr(2)Ta6Cr6 cuboctahedra, corners with four equivalent Cr(4)Ta5Cr6Si cuboctahedra, corners with ten equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, edges with two equivalent Cr(4)Ta5Cr6Si cuboctahedra, edges with four equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, faces with three equivalent Cr(1)Ta3Cr6Si3 cuboctahedra, faces with three equivalent Cr(2)Ta6Cr6 cuboctahedra, faces with four equivalent Cr(3)Ta4Cr6Si2 cuboctahedra, and faces with eight equivalent Cr(4)Ta5Cr6Si cuboctahedra. There are two shorter (2.35 Å) and two longer (2.49 Å) Cr(4)-Cr(4) bond lengths. The Cr(4)-Si(1) bond length is 2.82 Å. Si(1) is bonded in a 16-coordinate geometry to one Ta(3), three equivalent Ta(1), three equivalent Cr(1), three equivalent Cr(4), and six equivalent Cr(3) atoms.