Exploration of the СH3CN…HF complex in the gas phase with high-resolution FTIR spectroscopy and computational methods

Abstract This paper presents a comprehensive study of the IR absorption spectrum of the СH3CN … HF complex in the gas phase, including computation methods. The high resolution IR absorption spectra of the gaseous mixtures of the title complex were recorded in the region of 4000–2000 cm−1 at a resolution from 0.1 to 0.005 cm−1 with a Bruker IFS-120 HR vacuum Fourier-transform infrared spectrometer. The formation mechanism of the ν(HF) stretching band contour was explained. By utilizing DFT quantum chemical calculations we determined the equilibrium configuration and the geometric parameters, the harmonic vibrational frequencies, the dipole moments, and the binding energies of the СH3CN … HF complex in the mp2//311++G(3df,3pd) approximation. The three 3 D potential energy surfaces of the complex were evaluated, and the constructed graphs allowed us to reveal a link between the structural changes and the potential energies of the СH3CN … HF complex.