Np2S3 is Stibnite structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Np sites. In the first Np site, Np(1) is bonded to two equivalent S(1), two equivalent S(3), and three equivalent S(2) atoms to form a mixture of distorted edge and corner-sharing NpS7 pentagonal bipyramids. In the second Np site, Np(2) is bonded in a 8-coordinate geometry to two equivalent S(2), three equivalent S(1), and three equivalent S(3) atoms. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Np(1) and three equivalent Np(2) atoms to form a mixture of distorted edge and corner-sharing SNp5 trigonal bipyramids. In the second S site, S(2) is bonded to two equivalent Np(2) and three equivalent Np(1) atoms to form a mixture of edge and corner-sharing SNp5 square pyramids. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent Np(1) and three equivalent Np(2) atoms.
Np2S3 is Stibnite structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Np sites. In the first Np site, Np(1) is bonded to two equivalent S(1), two equivalent S(3), and three equivalent S(2) atoms to form a mixture of distorted edge and corner-sharing NpS7 pentagonal bipyramids. Both Np(1)-S(1) bond lengths are 2.84 Å. There is one shorter (2.83 Å) and one longer (2.88 Å) Np(1)-S(3) bond length. There are two shorter (2.81 Å) and one longer (2.84 Å) Np(1)-S(2) bond length. In the second Np site, Np(2) is bonded in a 8-coordinate geometry to two equivalent S(2), three equivalent S(1), and three equivalent S(3) atoms. Both Np(2)-S(2) bond lengths are 2.92 Å. There are two shorter (2.89 Å) and one longer (2.91 Å) Np(2)-S(1) bond length. There are two shorter (2.90 Å) and one longer (3.36 Å) Np(2)-S(3) bond length. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Np(1) and three equivalent Np(2) atoms to form a mixture of distorted edge and corner-sharing SNp5 trigonal bipyramids. In the second S site, S(2) is bonded to two equivalent Np(2) and three equivalent Np(1) atoms to form a mixture of edge and corner-sharing SNp5 square pyramids. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent Np(1) and three equivalent Np(2) atoms.