Crystal Structure of a Tetrameta‐Polyphosphate: Pb 2 Cs 3 (P 4 O 12 )(PO 3 ) 3

Chemical preparation and crystal structure of Pb 2 Cs 3 (P 4 O 12 )(PO 3 ) 3 are described. The triclinic unit cell has the following dimensions:space group is P 1 with Z = 2. The crystal structure has been solved by using 3350 unique reflexions with a final R value 0.048, The main outstanding feature of this compound rests on the coexistence in its atomic arrangement of two kinds of phosphate anions with different degrees of condensation: a tetrameric cyclic one (P 4 O 12 ) 4− and a linear infinite chain (PO 3 ) ∞ . The unit cell is crossed by two (PO 3 ) ∞ chains, related by centrosymmetry, running in planes perpendicular to the \documentclass{article}\pagestyle{empty}\begin{document}$ \overrightarrow {\rm c} $\end{document} axis at z ≃ 0.25 and 0.75. The two crystallographic independent P 4 O 12 4− ring anions are centrosymmetrical located around (0, 1/2, 0) and (0, 1/2, 1/2) inversion centers, half way between the (PO 3 ) ∞ chains. Sr 2 Cs 3 (P 4 O 12 )(PO 3 ) 3 is isotypic with the title compound.