Polyphosphides

The P ₄ ²⁻ anion has an aromatic character

Polyphosphides are polyphosphorus compounds in which the phosphorus atoms are present as anionic cage structures (so-called polyanions ). The compounds are extremely unstable and only stable and detectable at temperatures of liquid ammonia (−33.4 ° C to −77.4 ° C).

Manufacturing

Polyphosphides can be prepared from phosphane by deprotonation with gentle oxidation . The direct reaction of metals with white or red phosphorus at high temperatures and in the absence of air results in non-polymeric phosphides .

Known polyphosphides

Some polyphosphides
P 7 3−	P 11 3−
P 14 4−	P 22 4−

• P ₄ ²⁻ has an aromatic character and is therefore a planar ring with a P − P − P bond angle of ~ 90 ° (example Cs ₂ P ₄  · 2 NH ₃ , P − P bond lengths 215 pm ).
• P ₅ ^-
• P ₆ ⁴⁻
• P ₇ ³⁻ forms a cage structure with an equilateral P ₃ triangle as a base, which is bridged by a trigonal P ₄ pyramid as the "head". This structural element can also occur with higher homologues ([P ₇ ^- ] ) _{${\displaystyle \infty }$}
• P ₁₁ ³⁻
• P ₁₄ ⁴⁻ corresponds to a dimer of P ₇ ³⁻ , with two of the "head" phosphorus atoms connected.
• P ₁₆ ²⁻
• P ₁₉ ³⁻
• P ₂₁ ³⁻
• P ₃₀ N ⁵⁻ The phosphide cage contains a central nitrogen atom from the solvent ammonia. The anion structure is present in the solid as a dimer.
• P ₂₂ ⁴⁻ is made up of two bridged P ₁₁ ³⁻ cages

Chemical properties

Polyphosphides can be converted into the corresponding hydrogen polyphosphides by gentle protonation in liquid ammonia . These thus represent the links to the polyphosphines . Chain-like polyphosphides are isoelectronic to the corresponding polysulfides and are similar in structure.

See also : polysulfides

Web links

• Polyphosphides and hydrogen polyphosphides ( Memento from September 30, 2007 in the Internet Archive ) (PDF; 131 kB)

Individual evidence

1. ^ ^{A b c d e f} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 755-757.
2. ^ H. Graf: Dissertation, University of Karlsruhe (TH), 1998.