Zur Chemie und Strukturchemie der Phosphide und Polyphosphide. 26. Dibariumheptaphosphidchlorid Ba2P7Cl,eine Verbindung mit dem polycyclischen Anion P

Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 26. Dibariumheptaphosphidechloride Ba₂P₇Cl, a Compound with the Polycyclic Anion P Ba₂P₇Cl is formed by the synthesis of Ba₃P₁₄ from the elements in a melt of BaCl₂ (dehydrated) at 1170 K. The compound forms light rubyred platelets which decompose in protic systems immediately to phosphanes. Ba₂P₇Cl crystallizes in the space group P2₁/m with Z = 2 formular units (a = 1172.6(2) pm; b = 682.9(1) pm; c = 633.7(1) pm; β = 95.27(2)°). The structure (964 reflexions hkl, R = 0.035) is related to the NaCl type, in which the half of the anionic positions is occupied by the gravi-centers of the polycyclic anions P. The bond lengths d(P? P) show the typical topological dependence for the anionic heptaphosphanortricyclene system: (d : 226.4 pm in the three-membered ring; 214.5 pm ring to bridge; 217.2 pm bridge to bridge head). The Ba atoms are surrounded by 9 and 10 non metallic atoms, respectively. Cl^? is coordinated tetrahedrally by Ba.