Phosphinoborine Compounds: Mass Spectra and Pyrolysis

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Mass Spectrometry

Background:

• Organophosphorus and organoboron compounds are crucial in materials science and catalysis.
• Understanding the thermal stability and decomposition pathways of these compounds is essential for their application and safety.

Purpose of the Study:

• To investigate the mass spectra and pyrolysis behavior of tetramethylphosphinoborine trimer and P5(CH3)9B5H9.
• To elucidate the decomposition mechanisms and identify volatile products.

Main Methods:

• Mass spectrometry was used to analyze the compounds.
• Pyrolysis experiments were conducted at temperatures ranging from 300 to 500°C.
• Volatile products were monitored to understand decomposition trends.

Main Results:

• The mass spectrum of tetramethylphosphinoborine trimer showed P-B, B-C, and P-C bond cleavages.
• The mass spectrum of P5(CH3)9B5H9 was more complex, indicating methyl group redistribution.
• Both compounds decomposed completely within 4 hours at 450°C.
• Trimethylboron was a product of tetramethylphosphinoborine trimer pyrolysis but rapidly disappeared above 400°C.

Conclusions:

• The pyrolysis of these organophosphorus-organoboron compounds involves complex mechanisms with numerous unidentifiable intermediates.
• Complete decomposition occurs at moderate temperatures, suggesting potential limitations for high-temperature applications.
• The absence of ethane and elemental phosphorus in the products provides specific insights into the decomposition pathways.