Search

• Formation of four amines and ethers H-bonded complexes is established through acoustic method. • UV-Vis. Spectral data support the existence of such complexes in n-hexane. • Thermodynamic parameters K, ΔG, ΔH and ΔS obtained by acoustical and optical methods are reported. • ΔG values reveal thermodynamic stability and ΔH data show exothermic nature of complexes. • Structure of amine and ether influences the formation of these complexes. The present work deals with experimental determination of acoustical parameters to investigate the influence of structure of amines and ethers on thermodynamic properties of four hydrogen bonded complexes in n-hexane solvent at four different temperatures in the range 294.15 K-310.15 K. Benzyl amine (BA) and n-propyl amine (NPA) are used as H-donors while anisole (ANI) and diphenyl ether (DPE) act as H-acceptors. The existence of these H-bonded complexes in solution is also supported by UV spectral data. The formation constants (K) of the complexes determined by ultrasonic and UV-Vis. spectral methods at 303.15 K are comparable. Further, it is observed that the interactions in the aliphatic amine - aromatic ether systems are stronger than aralkyl amine (BA) – ether systems. The thermodynamic parameters confirm that all the four complexes are thermodynamically stable and formation of these complexes is exothermic. The sign of ΔS shows there are strong intermolecular interactions between amines and ethers in n-hexane medium. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Infrared spectrum of the adduct of H 2 S and NH 3 measured in solid argon matrices. • Anharmonic frequency calculations agreed well with the experimental values. • Binding energy of 8.6 kJ mol−1 (720 cm−1) calculated for the complex. Hydrogen bonding in S H⋯N systems has received little attention compared to other hydrogen bond motifs. To characterise S H⋯N bonding, infrared spectra of the most fundamental S H⋯N system—the H 2 S·NH 3 complex—were recorded in solid argon. These experiments were complemented by high level ab initio and density functional theory calculations. The H 2 S symmetric stretch was observed to shift by −155.3 cm−1 when mixed with NH 3 , while the NH 3 umbrella mode was found to shift by +31.8 cm−1. These, as well as deuterium and 15 N isotopologue studies indicated the formation of a complex. The structure of the H 2 S·NH 3 complex was determined to be almost identical to that of the H 2 O·NH 3 complex, with a nearly linear S H⋯N bond. A binding energy of 8.6 kJ mol−1 (720 cm−1) was calculated at the CCSD(T) level of theory extrapolated to the complete basis set limit. Anharmonic frequency calculations at the DSD-PBEP86-D3BJ/aug-cc-pV(D+d)Z level of theory produced frequencies with a RMSD of 13 cm−1 for the complex, relative to the experimental values. Comparison with previous work showed that the S H⋯N bond is weaker in H 2 S·NH 3 than the O H⋯N bond in the H 2 O·NH 3 system. [ABSTRACT FROM AUTHOR]