Nb6Cr7 is Frank-Kasper $\mu$ Phase structured and crystallizes in the trigonal R-3m space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 15-coordinate geometry to three equivalent Nb(1), six equivalent Nb(3), and six equivalent Cr(2) atoms. In the second Nb site, Nb(2) is bonded in a 16-coordinate geometry to one Nb(3), three equivalent Nb(2), three equivalent Cr(1), and nine equivalent Cr(2) atoms. In the third Nb site, Nb(3) is bonded in a 14-coordinate geometry to one Nb(2), one Nb(3), six equivalent Nb(1), and six equivalent Cr(2) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to six equivalent Nb(2) and six equivalent Cr(2) atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent Cr(2)Nb7Cr5 cuboctahedra, edges with six equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(2)Nb7Cr5 cuboctahedra. In the second Cr site, Cr(2) is bonded to two equivalent Nb(1), two equivalent Nb(3), three equivalent Nb(2), one Cr(1), and four equivalent Cr(2) atoms to form CrNb7Cr5 cuboctahedra that share corners with two equivalent Cr(1)Nb6Cr6 cuboctahedra, corners with thirteen equivalent Cr(2)Nb7Cr5 cuboctahedra, edges with five equivalent Cr(2)Nb7Cr5 cuboctahedra, faces with three equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with ten equivalent Cr(2)Nb7Cr5 cuboctahedra.
Nb6Cr7 is Frank-Kasper $\mu$ Phase structured and crystallizes in the trigonal R-3m space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 15-coordinate geometry to three equivalent Nb(1), six equivalent Nb(3), and six equivalent Cr(2) atoms. All Nb(1)-Nb(1) bond lengths are 2.84 Å. There are three shorter (3.12 Å) and three longer (3.14 Å) Nb(1)-Nb(3) bond lengths. There are three shorter (2.93 Å) and three longer (2.98 Å) Nb(1)-Cr(2) bond lengths. In the second Nb site, Nb(2) is bonded in a 16-coordinate geometry to one Nb(3), three equivalent Nb(2), three equivalent Cr(1), and nine equivalent Cr(2) atoms. The Nb(2)-Nb(3) bond length is 2.83 Å. All Nb(2)-Nb(2) bond lengths are 3.00 Å. All Nb(2)-Cr(1) bond lengths are 2.88 Å. There are three shorter (2.88 Å) and six longer (2.91 Å) Nb(2)-Cr(2) bond lengths. In the third Nb site, Nb(3) is bonded in a 14-coordinate geometry to one Nb(2), one Nb(3), six equivalent Nb(1), and six equivalent Cr(2) atoms. The Nb(3)-Nb(3) bond length is 2.63 Å. All Nb(3)-Cr(2) bond lengths are 2.77 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to six equivalent Nb(2) and six equivalent Cr(2) atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent Cr(2)Nb7Cr5 cuboctahedra, edges with six equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(2)Nb7Cr5 cuboctahedra. All Cr(1)-Cr(2) bond lengths are 2.49 Å. In the second Cr site, Cr(2) is bonded to two equivalent Nb(1), two equivalent Nb(3), three equivalent Nb(2), one Cr(1), and four equivalent Cr(2) atoms to form CrNb7Cr5 cuboctahedra that share corners with two equivalent Cr(1)Nb6Cr6 cuboctahedra, corners with thirteen equivalent Cr(2)Nb7Cr5 cuboctahedra, edges with five equivalent Cr(2)Nb7Cr5 cuboctahedra, faces with three equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with ten equivalent Cr(2)Nb7Cr5 cuboctahedra. There are two shorter (2.43 Å) and two longer (2.48 Å) Cr(2)-Cr(2) bond lengths.