Homoatomic cations: From [P₅]⁺ to [P₉]

Area of Science:

• Inorganic Chemistry
• Materials Science
• Synthetic Chemistry

Background:

• Classical synthesis methods are unsuitable for preparing phosphorus cations.
• Homopolyatomic phosphorus cations are of significant interest in cluster chemistry.
• Previous attempts to synthesize [P₉]⁺ salts faced limitations.

Purpose of the Study:

• To develop novel synthetic routes for [P₉]⁺ salts.
• To overcome limitations in classical synthesis of phosphorus cations.
• To explore the formation and structure of the [P₉]⁺ cation in the condensed phase.

Main Methods:

• Oxidation of elemental phosphorus (P₄) using specific oxidizing agents.
• Utilizing arene-stabilized cobalt(I) sandwich complexes as precursors.
• Reduction of a pre-formed phosphorus chloride cation with a gallium(I) source.

Main Results:

• Successful synthesis of [P₉]⁺ salts with various counterions ([F{Al(OR^F)₃}₂], [Al(OR^F)₄], and Ga₂Cl₇).
• Quantum chemical calculations suggest the involvement of a nido-[P₅]⁺ intermediate.
• Solid-state structure determination of [P₉][Ga₂Cl₇] reveals a D_2d-symmetric Zintl-type cage.

Conclusions:

• The developed synthetic approaches are effective for preparing [P₉]⁺ salts.
• These methods overcome limitations of classical synthesis for phosphorus cations.
• The study demonstrates potential for synthesizing other novel [P]⁺ cations in condensed phases.