Spectroscopic and theoretical investigation of solvent effect on N–H∙∙∙O, N–H∙∙∙N and N–H∙∙∙π interactions in complexes of N-monosubstituted benzamides

In this research, experimental and theoretical spectral analysis of N-monosubstituted benzamides was performed by mid-infrared spectroscopy and density functional theory. The MIR spectroscopic characteristics for N–H∙∙∙O, N–H∙∙∙N and N–H∙∙∙π hydrogen-bonded complexes and also the equilibrium constants for 1:1 complex formation are given. The structures of selected N-substituted benzamides (as proton donors), benzene, acetonitrile, and tetrahydrofuran (as proton acceptors), as well as their complexes, were optimised at the M06-2X/6–311++G(d,p) level of theory. The solvent effect on hydrogen-bonded complexes and the correlations between the equilibrium constants and molecular descriptors of N-monosubstituted benzamides were also investigated using a principal component analysis.