Base-Stabilized [PO]⁺ /[PO₂ ]⁺ Cations.

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Carbene Chemistry

Background:

• Singlet carbenes are versatile ligands in coordination chemistry.
• Phosphorus-oxygen cations are less explored due to stability challenges.
• Understanding electronic structure is key to predicting reactivity.

Purpose of the Study:

• To synthesize and characterize novel phosphorus oxide cations stabilized by singlet carbenes.
• To investigate the electronic structure and resultant reactivity of these unique cationic species.
• To explore their behavior as both ligands and electrophiles in chemical transformations.

Main Methods:

• Synthesis of [(BAC)2PO][BF4] (5) and [(BAC)2PO2][BF4] (4) using bis(diisopropylamino)cyclopropenylidene (BAC).
• Computational investigations to elucidate the electronic structure and resonance forms of the PO+ cation.
• Reactions with a transition-metal complex (K2PtCl4) and fluoride anion to probe reactivity.

Main Results:

• Successful preparation of PO+ and PO2+ salts coordinated to singlet carbenes.
• Computational analysis revealed the PO+ cation's electronic structure as a hybrid of charge-localized and delocalized forms, conferring ambiphilic reactivity.
• Compound 5 acted as a donor ligand, forming a platinum complex (6). Both 5 and 4 reacted as electrophiles with fluoride.

Conclusions:

• The study demonstrates the successful synthesis of novel phosphorus oxide cations stabilized by singlet carbenes.
• The unique electronic structure of the PO+ cation leads to versatile ambiphilic reactivity.
• These compounds serve as valuable synthons for both coordination chemistry and electrophilic transformations.