Nb4Fe(CS2)2 crystallizes in the monoclinic P2/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one C(2), two equivalent C(1), one S(1), and two equivalent S(2) atoms to form NbC3S3 octahedra that share corners with three equivalent Nb(1)C3S3 octahedra, corners with four equivalent Fe(1)S6 octahedra, edges with three equivalent Nb(1)C3S3 octahedra, and edges with six equivalent Nb(2)C3S3 octahedra. The corner-sharing octahedral tilt angles range from 0-46°. In the second Nb site, Nb(2) is bonded to one C(1), two equivalent C(2), one S(2), and two equivalent S(1) atoms to form NbC3S3 octahedra that share corners with two equivalent Fe(1)S6 octahedra, corners with three equivalent Nb(2)C3S3 octahedra, edges with three equivalent Nb(2)C3S3 octahedra, edges with six equivalent Nb(1)C3S3 octahedra, and  a faceface with one Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 0-47°. Fe(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form FeS6 octahedra that share corners with four equivalent Nb(2)C3S3 octahedra, corners with eight equivalent Nb(1)C3S3 octahedra, edges with two equivalent Fe(1)S6 octahedra, and faces with two equivalent Nb(2)C3S3 octahedra. The corner-sharing octahedral tilt angles range from 45-47°. There are two inequivalent C sites. In the first C site, C(1) is bonded to two equivalent Nb(2) and four equivalent Nb(1) atoms to form CNb6 octahedra that share corners with six equivalent S(2)Nb3Fe trigonal pyramids, edges with two equivalent C(1)Nb6 octahedra, edges with four equivalent C(2)Nb6 octahedra, and edges with two equivalent S(2)Nb3Fe trigonal pyramids. In the second C site, C(2) is bonded to two equivalent Nb(1) and four equivalent Nb(2) atoms to form CNb6 octahedra that share edges with two equivalent C(2)Nb6 octahedra, edges with four equivalent C(1)Nb6 octahedra, and edges with four equivalent S(2)Nb3Fe trigonal pyramids. There are two inequivalent S sites. In the first S site, S(1) is bonded in a 5-coordinate geometry to one Nb(1), two equivalent Nb(2), and two equivalent Fe(1) atoms. In the second S site, S(2) is bonded to one Nb(2), two equivalent Nb(1), and one Fe(1) atom to form distorted SNb3Fe trigonal pyramids that share corners with three equivalent C(1)Nb6 octahedra, corners with three equivalent S(2)Nb3Fe trigonal pyramids,  an edgeedge with one C(1)Nb6 octahedra, and edges with two equivalent C(2)Nb6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°.
Nb4Fe(CS2)2 crystallizes in the monoclinic P2/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one C(2), two equivalent C(1), one S(1), and two equivalent S(2) atoms to form NbC3S3 octahedra that share corners with three equivalent Nb(1)C3S3 octahedra, corners with four equivalent Fe(1)S6 octahedra, edges with three equivalent Nb(1)C3S3 octahedra, and edges with six equivalent Nb(2)C3S3 octahedra. The corner-sharing octahedral tilt angles range from 0-46°. The Nb(1)-C(2) bond length is 2.23 Å. Both Nb(1)-C(1) bond lengths are 2.25 Å. The Nb(1)-S(1) bond length is 2.56 Å. Both Nb(1)-S(2) bond lengths are 2.54 Å. In the second Nb site, Nb(2) is bonded to one C(1), two equivalent C(2), one S(2), and two equivalent S(1) atoms to form NbC3S3 octahedra that share corners with two equivalent Fe(1)S6 octahedra, corners with three equivalent Nb(2)C3S3 octahedra, edges with three equivalent Nb(2)C3S3 octahedra, edges with six equivalent Nb(1)C3S3 octahedra, and  a faceface with one Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 0-47°. The Nb(2)-C(1) bond length is 2.25 Å. Both Nb(2)-C(2) bond lengths are 2.22 Å. The Nb(2)-S(2) bond length is 2.55 Å. Both Nb(2)-S(1) bond lengths are 2.58 Å. Fe(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form FeS6 octahedra that share corners with four equivalent Nb(2)C3S3 octahedra, corners with eight equivalent Nb(1)C3S3 octahedra, edges with two equivalent Fe(1)S6 octahedra, and faces with two equivalent Nb(2)C3S3 octahedra. The corner-sharing octahedral tilt angles range from 45-47°. Both Fe(1)-S(2) bond lengths are 2.40 Å. All Fe(1)-S(1) bond lengths are 2.41 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded to two equivalent Nb(2) and four equivalent Nb(1) atoms to form CNb6 octahedra that share corners with six equivalent S(2)Nb3Fe trigonal pyramids, edges with two equivalent C(1)Nb6 octahedra, edges with four equivalent C(2)Nb6 octahedra, and edges with two equivalent S(2)Nb3Fe trigonal pyramids. In the second C site, C(2) is bonded to two equivalent Nb(1) and four equivalent Nb(2) atoms to form CNb6 octahedra that share edges with two equivalent C(2)Nb6 octahedra, edges with four equivalent C(1)Nb6 octahedra, and edges with four equivalent S(2)Nb3Fe trigonal pyramids. There are two inequivalent S sites. In the first S site, S(1) is bonded in a 5-coordinate geometry to one Nb(1), two equivalent Nb(2), and two equivalent Fe(1) atoms. In the second S site, S(2) is bonded to one Nb(2), two equivalent Nb(1), and one Fe(1) atom to form distorted SNb3Fe trigonal pyramids that share corners with three equivalent C(1)Nb6 octahedra, corners with three equivalent S(2)Nb3Fe trigonal pyramids,  an edgeedge with one C(1)Nb6 octahedra, and edges with two equivalent C(2)Nb6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°.