[en] Niobium pentachloride reacts with trithiazylchloride in CCl₄-suspension forming the complex Cl₅Nb-NSCl which forms red crystals that are very sensitive to moisture. According to the vibrational spectrum and the crystal structure determination the compound consists of monomeric units in which NbCl₅ is bonded to NSCl in a relatively loose manner via the nitrogen atom. The crystal structure was determined with X-ray diffraction data and was refined to a residual index of R = 0.019 for 1879 reflexions. Cl₅NbNSCl crystallizes in the triclinic space group P1-bar with the lattice constants a = 636.7, b = 1215.5, c = 1266.8 pm, α = 83.32, β = 78.52 and γ = 82.26⁰ and with four molecules per unit cell. There are two crystallographically independent molecules which differ somewhat in their geometry. (author)