Coordination of methanol clusters to benzene: a computational study

Area of Science:

• Theoretical Chemistry
• Computational Chemistry
• Physical Chemistry

Background:

• Benzene-methanol mixtures exhibit azeotropic behavior, necessitating a deeper understanding of their molecular interactions.
• Microsolvation of benzene by methanol is a key factor in describing these interactions.
• Accurate theoretical models are required to elucidate the complex structures and energetics of benzene-methanol clusters.

Purpose of the Study:

• To investigate benzene-methanol cluster structures using advanced theoretical methods.
• To describe the microsolvation of benzene by methanol.
• To model the benzene-methanol azeotrope at a molecular level.

Main Methods:

• Ab initio calculations, specifically MP2 with basis sets up to aug-cc-pVxZ, were employed.
• Basis Set Superposition Error (BSSE) correction and complete basis set (CBS) extrapolation were utilized.
• Density Functional Theory (DFT) methods (DFTB+, MPWB1K, M06-2X) were applied for smaller clusters.

Main Results:

• The most stable C(6)H(6)(MeOH)(3) cluster features a hydrogen-bonded methanol trimer interacting with benzene.
• Larger clusters (n ≥ 4) show cyclic methanol subclusters interacting with benzene via dispersive forces.
• The benzene-methanol azeotrope modeling revealed stable structures with T-shaped or parallel displaced benzene dimers interacting with methanol trimers.

Conclusions:

• The study provides detailed structural and energetic insights into benzene-methanol clusters.
• The findings elucidate the role of hydrogen bonding and dispersive forces in microsolvation and azeotrope formation.
• Computational results offer a molecular-level understanding of benzene-methanol interactions relevant to physical chemistry and mixture behavior.