Our research is focused on the ab initio calculations of the equilibrium structures, binding energies, harmonic and anharmonic vibrational frequencies of a hydrogen-bonded complex, which is formed between formaldehyde H2CO and hydrogen fluoride HF, using the Gaussian 09 package of programs with full 6311++G(3df, 3pd) basis sets in the MP2 second-order perturbation theory and CCSD(T) methods. Harmonic and anharmonic vibrational frequencies and intensities of the H2CO···HF complex were calculated by the Gaussian 16 package programs within the same approximation. Geometric changes and frequency shifts at the complex formation were evaluated. The H2CO···HF complex formation energy and the dipole moment were calculated in the CCSD(T)6311++G(3df, 3pd) approximation to be equal, respectively, to 7.78 kcal/mol and 4.2 D. Changes of the geometric, spectral, and energetic parameters of the complex proved the existence of a stable hydrogen bond F–H···O=CH2 between the components.

Intra- and intermolecular interactions in liquid ethylene glycol have been studied using the Raman spectroscopy method and non-empirical calculations. The results of non-empirical calculations show that an intermolecular hydrogen bond is formed between the hydrogen atom of the OH group in one ethylene glycol molecule and the oxygen atom in the other molecule. The formation of this bond gives rise to a substantial redistribution of charges between those atoms, which, nevertheless, insignificantly changes the bond length. In the corresponding Raman spectra, the presence of hydrogen bonds between the ethylene glycol molecules manifests itself as the band asymmetry and splitting.

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In this work, equilibrium geometry, bond energy, harmonic and anharmonic spectral parameters of the monomers of CH3CHO, HF molecules and CH3CHO···HF, CH3COH···FH complexes were calculated using the set of bases MP2/6-311++G(3df, 3pd). Anharmonic calculations were performed using second-order vibration theory. The binding energies of CH3CHO ··· HF and CH3COH ··· FH complexes are 10.1 kcal/mol and 1.7 kcal/mol, respectively.