Nb2NiS4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one S(2), two equivalent S(4), and three equivalent S(1) atoms to form edge-sharing NbS6 octahedra. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one S(1), two equivalent S(2), and three equivalent S(3) atoms. Ni(1) is bonded in a distorted trigonal planar geometry to one S(4) and two equivalent S(2) atoms. There are four inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Nb(2) and three equivalent Nb(1) atoms. In the second S site, S(2) is bonded to one Nb(1), two equivalent Nb(2), and two equivalent Ni(1) atoms to form distorted edge-sharing SNb3Ni2 square pyramids. In the third S site, S(3) is bonded in a distorted T-shaped geometry to three equivalent Nb(2) atoms. In the fourth S site, S(4) is bonded in a distorted trigonal planar geometry to two equivalent Nb(1) and one Ni(1) atom.
Nb2NiS4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one S(2), two equivalent S(4), and three equivalent S(1) atoms to form edge-sharing NbS6 octahedra. The Nb(1)-S(2) bond length is 2.54 Å. Both Nb(1)-S(4) bond lengths are 2.45 Å. There is one shorter (2.46 Å) and two longer (2.54 Å) Nb(1)-S(1) bond lengths. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one S(1), two equivalent S(2), and three equivalent S(3) atoms. The Nb(2)-S(1) bond length is 2.45 Å. Both Nb(2)-S(2) bond lengths are 2.55 Å. There are two shorter (2.49 Å) and one longer (2.54 Å) Nb(2)-S(3) bond length. Ni(1) is bonded in a distorted trigonal planar geometry to one S(4) and two equivalent S(2) atoms. The Ni(1)-S(4) bond length is 2.12 Å. Both Ni(1)-S(2) bond lengths are 2.16 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Nb(2) and three equivalent Nb(1) atoms. In the second S site, S(2) is bonded to one Nb(1), two equivalent Nb(2), and two equivalent Ni(1) atoms to form distorted edge-sharing SNb3Ni2 square pyramids. In the third S site, S(3) is bonded in a distorted T-shaped geometry to three equivalent Nb(2) atoms. In the fourth S site, S(4) is bonded in a distorted trigonal planar geometry to two equivalent Nb(1) and one Ni(1) atom.