Non-covalent interactions of nitrous oxide with aromatic compounds: Spectroscopic and computational evidence for the formation of 1:1 complexes

We present the first study of intermolecular interactions between nitrous oxide (N₂O) and three representative aromatic compounds (ACs): phenol, cresol, and toluene. The infrared spectroscopic experiments were performed in a Ne matrix and were supported by high-level quantum chemical calculations. Comparisons of the calculated and experimental vibrational spectra provide direct identification and characterization of the 1:1 N₂O-AC complexes. Our results show that N₂O is capable of forming non-covalently bonded complexes with ACs. Complex formation is dominated by dispersion forces, and the interaction energies are relatively low (about -3 kcal mol^-1); however, the complexes are clearly detected by frequency shifts of the characteristic bands. These results suggest that N₂O can be bound to the amino-acid residues tyrosine or phenylalanine in the form of π complexes.