Nb(1.30)Cr(0.70)S(5): a layered ternary mixed-metal sulfide.

The new layered ternary sulfide, Nb(1.30)Cr(0.70)S(5), niobium chromium penta-sulfide, is isostructural with the solid solution Nb(1+x)V(1-x)S(5) and belongs to the FeNb(3)Se(10) structure type. Each layer is composed of two unique chains of face-sharing [NbS(8)] bicapped trigonal prisms (m symmetry) and edge-sharing [MS(6)] (M= Nb, Cr) octa-hedra (m symmetry). One of the two metal sites is occupied by statistically disordered Nb and Cr atoms, with 0.3 and 0.7 occupancy, respectively. The chains are connected along the c axis, forming two-dimensional layers, which then stack on top of each other to complete the three dimensional structure. As a result, an undulating van der Waals gap is found between the layers.