Deciphering the non-covalent interactions in the furan⋯hexane complex using rotational spectroscopy and theoretical...

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Computational Chemistry

Background:

• Furan is a planar molecule with a single stable conformation.
• n-Hexane exhibits conformational isomerism, existing in multiple stable forms.
• Understanding binary complexes is crucial for molecular interactions.

Purpose of the Study:

• To investigate the structure and stability of the furan-n-hexane binary complex.
• To explore the conformational landscape of the complex using computational methods.
• To identify the dominant intermolecular interactions responsible for complex formation.

Main Methods:

• Chirped pulse Fourier transform microwave spectroscopy (2-6 GHz).
• Semiempirical conformational search using CREST.
• Quantum chemical calculations (B3LYP-D3BJ/def2-TZVP, MP2, CCSD(T)-F12) for geometry optimization and energy analysis.
• Non-covalent interaction (NCI) and principal interacting orbital (PIO) analyses.

Main Results:

• Identified 34 stable minima within a 5 kJ mol-1 energy window for the furan-n-hexane complex.
• The three most stable conformers incorporate the most stable n-hexane subunit.
• Low energy barriers were found for conformational interconversion between the stable minima.
• Synergistic πfuran → σ*hexane and σhexane → π*furan interactions were identified as key stabilizing forces.

Conclusions:

• The study elucidates the conformational preferences and stabilization mechanisms of the furan-n-hexane complex.
• Microwave spectroscopy combined with computational chemistry provides detailed insights into non-covalent interactions.
• The findings contribute to the understanding of molecular recognition and complex formation in gas-phase chemistry.