The crystal structure of 3-R Nb1.06S2

The X-ray single crystal structure of 3-R Nb_1.06S₂ has been determined. The material crystallizes in the space group R_3m with a = 3.3285(4) and c = 17.910(4) Å when indexed on a hexagonal lattice. The structure was refined by full matrix least squares procedures to a final residual of R = 0.026 based on 79 observed (I > 3σ_I) reflections. The sulfurs form closest-packed layers with the majority of the metal in sheets of trigonal prismatic sites. A small portion of niobium was found to occupy octahedral sites, between the van der Waals gaps of the sulfur lattice. Niobium in the van der Waals region is trigonally distorted from octahedral symmetry, with niobium-sulfur distances of 2.234(8) and 2.577(11) Å, because of repulsion from niobium in adjacent trigonal prismatic layers.