Borane-Stabilized Isomeric Dimers of the Phosphaethynolate Anion

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Inorganic Chemistry

Background:

• The phosphaethynolate anion ([PCO]^-) is a unique inorganic species with interesting reactivity.
• Boranes are versatile Lewis acids used in various chemical transformations.

Purpose of the Study:

• To investigate the reaction pathways between the phosphaethynolate anion and diverse boranes.
• To characterize the structures and bonding of the resulting dimeric anions.

Main Methods:

• Reactions were carried out under inert atmosphere conditions.
• Product characterization involved spectroscopic techniques and X-ray crystallography.
• Computational studies were employed to understand electronic and steric influences.

Main Results:

• Reaction with BPh₃ yielded a dimeric anion with P-B bonds, prone to dissociation.
• B(C₆ F₅ )₃ formed a less symmetric dimer featuring both P-B and P-O bonds.
• Less sterically hindered boranes, HB(C₆ F₅ )₂ and H₂ B(C₆ F₅ ), resulted in isomers with both boranes bound to the phosphorus atom.

Conclusions:

• The study revealed diverse binding modes of the phosphaethynolate anion with boranes.
• Thermodynamic preferences for P-coordination were observed.
• Electronic and steric effects significantly dictate the final structure of the dianionic dimers.