Nb8Zn4C3 is H-Phase-like structured and crystallizes in the cubic Fd-3m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 3-coordinate geometry to four equivalent Zn(1), one C(2), and two equivalent C(1) atoms. In the second Nb site, Nb(2) is bonded to six equivalent Zn(1) atoms to form distorted edge-sharing NbZn6 cuboctahedra. Zn(1) is bonded in a 12-coordinate geometry to three equivalent Nb(2), six equivalent Nb(1), and three equivalent Zn(1) atoms. There are two inequivalent C sites. In the first C site, C(2) is bonded to six equivalent Nb(1) atoms to form face-sharing CNb6 octahedra. In the second C site, C(1) is bonded to six equivalent Nb(1) atoms to form a mixture of corner and face-sharing CNb6 octahedra. The corner-sharing octahedral tilt angles are 40°.
Nb8Zn4C3 is H-Phase-like structured and crystallizes in the cubic Fd-3m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 3-coordinate geometry to four equivalent Zn(1), one C(2), and two equivalent C(1) atoms. There are two shorter (2.78 Å) and two longer (3.06 Å) Nb(1)-Zn(1) bond lengths. The Nb(1)-C(2) bond length is 2.28 Å. Both Nb(1)-C(1) bond lengths are 2.26 Å. In the second Nb site, Nb(2) is bonded to six equivalent Zn(1) atoms to form distorted edge-sharing NbZn6 cuboctahedra. All Nb(2)-Zn(1) bond lengths are 2.63 Å. Zn(1) is bonded in a 12-coordinate geometry to three equivalent Nb(2), six equivalent Nb(1), and three equivalent Zn(1) atoms. All Zn(1)-Zn(1) bond lengths are 2.96 Å. There are two inequivalent C sites. In the first C site, C(2) is bonded to six equivalent Nb(1) atoms to form face-sharing CNb6 octahedra. In the second C site, C(1) is bonded to six equivalent Nb(1) atoms to form a mixture of corner and face-sharing CNb6 octahedra. The corner-sharing octahedral tilt angles are 40°.