Die Molekulare Zusammensetzung von erstarrten Phosphor-Schwefel-Schmelzen und die Kristallstruktur von β-P4S6

The Molecular Composition of Solidified Phosphorus-Sulfur Melts and the Crystal Structure of β-P₄S₆ Phosphorus sulfur melts were annealed for one week at 673 K and then quenched in ice water. The solids were dissolved in CS₂ and the concentrations of phosphorus sulfides were determined by ³¹P NMR spectroscopy. Samples containing between 44 and 70 mol% sulfur dissolved completely in CS₂. Between 0 and 42 mol% remains an insoluble residue of red phosphorus. Above 72 mol% it consisted of sulfur chains linked by phosphorus atoms. The solutions contained mainly the congruently melting compounds P₄S₃, P₄S₇, and P₄S₁₀ having maximum concentrations at their stoichiometric compositions. Other compounds P₄S_n (n = 4–9) which decompose on heating, according to the phase diagram, were also found in surprisingly high concentrations. One of these was β-P₄S₆ which crystallizes in the monoclinic space group P2₁/c with the lattice parameters a = 702.4(2), b = 1 205.6(2), c = 1 148.9(6) pm and β = 103.4(2)°. Reaction of white phosphorus with sulfur was also investigated. In contrast to the results of previous authors, who described the system P₄–S₈ below 373 K as eutectic, we found that the elements reacted below this temperature.