| Abstract: | Nitride Sulfide Chlorides of the Lanthanides. III. Synthesis and Crystal Structure of Pr5N3S2Cl2 By reacting praseodymium with sulfur, sodium azide and praseodymium trichloride in sealed, evacuated silica tubes (850°C, 7 d), the nitride sulfide chloride Pr5N3S2Cl2 is obtained in case of a 4:2:1:1 molar ratio of the reactants (Pr:S:NaN3:PrCl3). A slight excess of trichloride or the addition of NaCl as a flux supports the yield of brownish red, rod-shaped transparent crystals which prove to be stable against hydrolysis. The crystal structure (monoclinic, C2/m (no. 12), a = 1540.2(1), b = 400.92(3), c = 1656.3(1) pm, β = 101.24(1)°, Z = 4, R = 0.039, Rw = 0.028) was determined by means of X-ray single crystal data. Thus five crystallographically different cations (Pr3+) are present which with three distinct kinds of nitride anions (N3?) build up two types of translationally commensurate chains from interconnected NPr4] tetrahedra. With an additional edge per “chain-link” in chain I, two single chains  NPr3/3ePr1/1t]3+ (? NPr2]3+) of cis-edge connected NPr4] tetrahedra (known from the Sm4N2S3-type structure) are condensed into the double chain  (N1){(Pr1)(2+2)/(2+2)e,e(Pr2)(2+1)/(2+1)e,v}(N2)(Pr3)1/1t]3+ (? N2Pr3]3+). Chain II consists of two single chains  NPr2/2vPr2/1t] 6+ (? NPr3]6+) of vertex-connected NPr4] tetrahedra (known from the Sm3NS3-type structure), which are condensed to the double chain  (N3)(Pr4)2/2e(Pr5)2/2v]3+ (? NPr2]3+) via an additional edge per “chain-link” too. Both types of chains are bundled along 010] like a closest packing of rods. Four crystallographically different but by X-ray diffraction indistinguishable anions S2? and Cl? hold both cationic double chains together and also adjust the charge balance in a molar ratio of 1 : 1. |
