Be8NbCr3 crystallizes in the trigonal P3m1 space group. There are four inequivalent Be sites. In the first Be site, Be(1) is bonded to three equivalent Be(3), three equivalent Be(4), three equivalent Nb(1), and three equivalent Cr(1) atoms to form BeBe6Nb3Cr3 cuboctahedra that share corners with six equivalent Be(3)Be6Nb2Cr4 cuboctahedra, corners with six equivalent Be(4)Be6NbCr5 cuboctahedra, edges with six equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with two equivalent Be(2)Be6Cr6 cuboctahedra, faces with nine equivalent Be(3)Be6Nb2Cr4 cuboctahedra, and faces with nine equivalent Be(4)Be6NbCr5 cuboctahedra. In the second Be site, Be(2) is bonded to three equivalent Be(3), three equivalent Be(4), three equivalent Cr(2), and three equivalent Cr(3) atoms to form BeBe6Cr6 cuboctahedra that share corners with six equivalent Be(3)Be6Nb2Cr4 cuboctahedra, corners with six equivalent Be(4)Be6NbCr5 cuboctahedra, edges with six equivalent Be(2)Be6Cr6 cuboctahedra, faces with two equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with nine equivalent Be(3)Be6Nb2Cr4 cuboctahedra, and faces with nine equivalent Be(4)Be6NbCr5 cuboctahedra. In the third Be site, Be(3) is bonded to one Be(1), one Be(2), four equivalent Be(3), two equivalent Nb(1), one Cr(1), one Cr(2), and two equivalent Cr(3) atoms to form BeBe6Nb2Cr4 cuboctahedra that share corners with two equivalent Be(2)Be6Cr6 cuboctahedra, corners with two equivalent Be(1)Be6Nb3Cr3 cuboctahedra, corners with four equivalent Be(3)Be6Nb2Cr4 cuboctahedra, corners with ten equivalent Be(4)Be6NbCr5 cuboctahedra, edges with two equivalent Be(3)Be6Nb2Cr4 cuboctahedra, edges with four equivalent Be(4)Be6NbCr5 cuboctahedra, faces with three equivalent Be(2)Be6Cr6 cuboctahedra, faces with three equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with four equivalent Be(4)Be6NbCr5 cuboctahedra, and faces with eight equivalent Be(3)Be6Nb2Cr4 cuboctahedra. In the fourth Be site, Be(4) is bonded to one Be(1), one Be(2), four equivalent Be(4), one Nb(1), one Cr(3), two equivalent Cr(1), and two equivalent Cr(2) atoms to form BeBe6NbCr5 cuboctahedra that share corners with two equivalent Be(2)Be6Cr6 cuboctahedra, corners with two equivalent Be(1)Be6Nb3Cr3 cuboctahedra, corners with four equivalent Be(4)Be6NbCr5 cuboctahedra, corners with ten equivalent Be(3)Be6Nb2Cr4 cuboctahedra, edges with two equivalent Be(4)Be6NbCr5 cuboctahedra, edges with four equivalent Be(3)Be6Nb2Cr4 cuboctahedra, faces with three equivalent Be(2)Be6Cr6 cuboctahedra, faces with three equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with four equivalent Be(3)Be6Nb2Cr4 cuboctahedra, and faces with eight equivalent Be(4)Be6NbCr5 cuboctahedra. Nb(1) is bonded in a 16-coordinate geometry to three equivalent Be(1), three equivalent Be(4), six equivalent Be(3), one Cr(3), and three equivalent Cr(1) atoms. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 16-coordinate geometry to three equivalent Be(1), three equivalent Be(3), six equivalent Be(4), three equivalent Nb(1), and one Cr(2) atom. In the second Cr site, Cr(2) is bonded in a 16-coordinate geometry to three equivalent Be(2), three equivalent Be(3), six equivalent Be(4), one Cr(1), and three equivalent Cr(3) atoms. In the third Cr site, Cr(3) is bonded in a 16-coordinate geometry to three equivalent Be(2), three equivalent Be(4), six equivalent Be(3), one Nb(1), and three equivalent Cr(2) atoms.
Be8NbCr3 crystallizes in the trigonal P3m1 space group. There are four inequivalent Be sites. In the first Be site, Be(1) is bonded to three equivalent Be(3), three equivalent Be(4), three equivalent Nb(1), and three equivalent Cr(1) atoms to form BeBe6Nb3Cr3 cuboctahedra that share corners with six equivalent Be(3)Be6Nb2Cr4 cuboctahedra, corners with six equivalent Be(4)Be6NbCr5 cuboctahedra, edges with six equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with two equivalent Be(2)Be6Cr6 cuboctahedra, faces with nine equivalent Be(3)Be6Nb2Cr4 cuboctahedra, and faces with nine equivalent Be(4)Be6NbCr5 cuboctahedra. All Be(1)-Be(3) bond lengths are 2.26 Å. All Be(1)-Be(4) bond lengths are 2.19 Å. All Be(1)-Nb(1) bond lengths are 2.54 Å. All Be(1)-Cr(1) bond lengths are 2.55 Å. In the second Be site, Be(2) is bonded to three equivalent Be(3), three equivalent Be(4), three equivalent Cr(2), and three equivalent Cr(3) atoms to form BeBe6Cr6 cuboctahedra that share corners with six equivalent Be(3)Be6Nb2Cr4 cuboctahedra, corners with six equivalent Be(4)Be6NbCr5 cuboctahedra, edges with six equivalent Be(2)Be6Cr6 cuboctahedra, faces with two equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with nine equivalent Be(3)Be6Nb2Cr4 cuboctahedra, and faces with nine equivalent Be(4)Be6NbCr5 cuboctahedra. All Be(2)-Be(3) bond lengths are 2.13 Å. All Be(2)-Be(4) bond lengths are 2.13 Å. All Be(2)-Cr(2) bond lengths are 2.54 Å. All Be(2)-Cr(3) bond lengths are 2.53 Å. In the third Be site, Be(3) is bonded to one Be(1), one Be(2), four equivalent Be(3), two equivalent Nb(1), one Cr(1), one Cr(2), and two equivalent Cr(3) atoms to form BeBe6Nb2Cr4 cuboctahedra that share corners with two equivalent Be(2)Be6Cr6 cuboctahedra, corners with two equivalent Be(1)Be6Nb3Cr3 cuboctahedra, corners with four equivalent Be(3)Be6Nb2Cr4 cuboctahedra, corners with ten equivalent Be(4)Be6NbCr5 cuboctahedra, edges with two equivalent Be(3)Be6Nb2Cr4 cuboctahedra, edges with four equivalent Be(4)Be6NbCr5 cuboctahedra, faces with three equivalent Be(2)Be6Cr6 cuboctahedra, faces with three equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with four equivalent Be(4)Be6NbCr5 cuboctahedra, and faces with eight equivalent Be(3)Be6Nb2Cr4 cuboctahedra. There are two shorter (2.12 Å) and two longer (2.21 Å) Be(3)-Be(3) bond lengths. Both Be(3)-Nb(1) bond lengths are 2.57 Å. The Be(3)-Cr(1) bond length is 2.68 Å. The Be(3)-Cr(2) bond length is 2.50 Å. Both Be(3)-Cr(3) bond lengths are 2.52 Å. In the fourth Be site, Be(4) is bonded to one Be(1), one Be(2), four equivalent Be(4), one Nb(1), one Cr(3), two equivalent Cr(1), and two equivalent Cr(2) atoms to form BeBe6NbCr5 cuboctahedra that share corners with two equivalent Be(2)Be6Cr6 cuboctahedra, corners with two equivalent Be(1)Be6Nb3Cr3 cuboctahedra, corners with four equivalent Be(4)Be6NbCr5 cuboctahedra, corners with ten equivalent Be(3)Be6Nb2Cr4 cuboctahedra, edges with two equivalent Be(4)Be6NbCr5 cuboctahedra, edges with four equivalent Be(3)Be6Nb2Cr4 cuboctahedra, faces with three equivalent Be(2)Be6Cr6 cuboctahedra, faces with three equivalent Be(1)Be6Nb3Cr3 cuboctahedra, faces with four equivalent Be(3)Be6Nb2Cr4 cuboctahedra, and faces with eight equivalent Be(4)Be6NbCr5 cuboctahedra. There are two shorter (2.12 Å) and two longer (2.20 Å) Be(4)-Be(4) bond lengths. The Be(4)-Nb(1) bond length is 2.58 Å. The Be(4)-Cr(3) bond length is 2.46 Å. Both Be(4)-Cr(1) bond lengths are 2.51 Å. Both Be(4)-Cr(2) bond lengths are 2.49 Å. Nb(1) is bonded in a 16-coordinate geometry to three equivalent Be(1), three equivalent Be(4), six equivalent Be(3), one Cr(3), and three equivalent Cr(1) atoms. The Nb(1)-Cr(3) bond length is 2.68 Å. All Nb(1)-Cr(1) bond lengths are 2.69 Å. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 16-coordinate geometry to three equivalent Be(1), three equivalent Be(3), six equivalent Be(4), three equivalent Nb(1), and one Cr(2) atom. The Cr(1)-Cr(2) bond length is 2.52 Å. In the second Cr site, Cr(2) is bonded in a 16-coordinate geometry to three equivalent Be(2), three equivalent Be(3), six equivalent Be(4), one Cr(1), and three equivalent Cr(3) atoms. All Cr(2)-Cr(3) bond lengths are 2.65 Å. In the third Cr site, Cr(3) is bonded in a 16-coordinate geometry to three equivalent Be(2), three equivalent Be(4), six equivalent Be(3), one Nb(1), and three equivalent Cr(2) atoms.