NbCr4Si crystallizes in the trigonal P-3m1 space group. Nb(1) is bonded in a 16-coordinate geometry to three equivalent Nb(1), three equivalent Cr(1), nine equivalent Cr(3), and one Si(1) atom. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to six equivalent Nb(1) and six equivalent Cr(3) atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, edges with six equivalent Cr(1)Nb6Cr6 cuboctahedra, faces with two equivalent Cr(2)Cr6Si6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Cr6Si3 cuboctahedra. In the second Cr site, Cr(2) is bonded to six equivalent Cr(3) and six equivalent Si(1) atoms to form CrCr6Si6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, edges with six equivalent Cr(2)Cr6Si6 cuboctahedra, faces with two equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Cr6Si3 cuboctahedra. In the third Cr site, Cr(3) is bonded to three equivalent Nb(1), one Cr(1), one Cr(2), four equivalent Cr(3), and three equivalent Si(1) atoms to form CrNb3Cr6Si3 cuboctahedra that share corners with two equivalent Cr(2)Cr6Si6 cuboctahedra, corners with two equivalent Cr(1)Nb6Cr6 cuboctahedra, corners with fourteen equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, edges with six equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, faces with three equivalent Cr(2)Cr6Si6 cuboctahedra, faces with three equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with twelve equivalent Cr(3)Nb3Cr6Si3 cuboctahedra. Si(1) is bonded in a 13-coordinate geometry to one Nb(1), three equivalent Cr(2), and nine equivalent Cr(3) atoms.
NbCr4Si crystallizes in the trigonal P-3m1 space group. Nb(1) is bonded in a 16-coordinate geometry to three equivalent Nb(1), three equivalent Cr(1), nine equivalent Cr(3), and one Si(1) atom. All Nb(1)-Nb(1) bond lengths are 3.00 Å. All Nb(1)-Cr(1) bond lengths are 2.86 Å. There are six shorter (2.85 Å) and three longer (2.86 Å) Nb(1)-Cr(3) bond lengths. The Nb(1)-Si(1) bond length is 2.79 Å. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to six equivalent Nb(1) and six equivalent Cr(3) atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, edges with six equivalent Cr(1)Nb6Cr6 cuboctahedra, faces with two equivalent Cr(2)Cr6Si6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Cr6Si3 cuboctahedra. All Cr(1)-Cr(3) bond lengths are 2.47 Å. In the second Cr site, Cr(2) is bonded to six equivalent Cr(3) and six equivalent Si(1) atoms to form CrCr6Si6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, edges with six equivalent Cr(2)Cr6Si6 cuboctahedra, faces with two equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Cr6Si3 cuboctahedra. All Cr(2)-Cr(3) bond lengths are 2.33 Å. All Cr(2)-Si(1) bond lengths are 2.86 Å. In the third Cr site, Cr(3) is bonded to three equivalent Nb(1), one Cr(1), one Cr(2), four equivalent Cr(3), and three equivalent Si(1) atoms to form CrNb3Cr6Si3 cuboctahedra that share corners with two equivalent Cr(2)Cr6Si6 cuboctahedra, corners with two equivalent Cr(1)Nb6Cr6 cuboctahedra, corners with fourteen equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, edges with six equivalent Cr(3)Nb3Cr6Si3 cuboctahedra, faces with three equivalent Cr(2)Cr6Si6 cuboctahedra, faces with three equivalent Cr(1)Nb6Cr6 cuboctahedra, and faces with twelve equivalent Cr(3)Nb3Cr6Si3 cuboctahedra. There are two shorter (2.37 Å) and two longer (2.51 Å) Cr(3)-Cr(3) bond lengths. There is one shorter (2.71 Å) and two longer (2.76 Å) Cr(3)-Si(1) bond lengths. Si(1) is bonded in a 13-coordinate geometry to one Nb(1), three equivalent Cr(2), and nine equivalent Cr(3) atoms.