Theoretical study of reaction pathways to borazine

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Theoretical Chemistry

Background:

• Borazine ((HBNH)3) is a key inorganic compound with diverse applications.
• Understanding the synthesis pathways of borazine is crucial for optimizing its production.
• Computational methods provide valuable insights into reaction mechanisms and energetics.

Purpose of the Study:

• To computationally investigate four distinct reaction pathways for synthesizing borazine from diborane and ammonia.
• To identify the lowest-energy and kinetically favored pathways for borazine formation.
• To explore the role of various intermediates in the synthesis of borazine.

Main Methods:

• Density functional theory (DFT) calculations were employed, specifically using the B3LYP functional.
• The study utilized the 6-311+G(2d,p) basis set for frequency calculations and the 6-31G(d) basis set for geometry optimizations.
• Four potential reaction pathways were analyzed to determine their relative energies and kinetic favorability.

Main Results:

• The cycloaddition of H2BNH2 to 1,3-diaza-2,4-diborabuta-1,3-diene followed by H2 elimination was identified as the lowest-energy pathway to borazine.
• Other pathways involving intermediates like 1,3,5-triaza-2,4,6-triborahexatriene were also investigated.
• Gas-phase kinetic favorability was predicted for pathways involving the formation and electrocyclization of 1,3,5-triaza-2,4,6-triborahexatriene and the cycloaddition of H2BNH2.

Conclusions:

• The study elucidates the most efficient computational pathway for borazine synthesis.
• Kinetic factors favor specific reaction routes under gas-phase conditions.
• Under certain concentration and temperature conditions, polyolefin formation can compete with borazine precursor formation.