Specific interactions in N-ylid solutions, studied by nuclear magnetic resonance and electronic absorption spectroscopy

Compounds with basic character, N-ylids can be involved in specific interactions with protic solvents. Consequently, “long range” (universal) and “short range” (specific) forces act simultaneously in the protic solutions of N-ylids. The contributions of these interactions to the total spectral shift measured in the Electronic Absorption Spectra (EAS) were separated on the basis of solvatochromic effects.Supplemental spectral shifts measured in protic solvents compared with aprotic ones increases with the chemical shift of –OH signal from the 1H Nuclear Magnetic Resonance (NMR) spectra of the protic solvents.Important information about the strength of the specific interactions was obtained from the spectral study of N-ylids ternary solutions in binary solvents with protic and non-protic molecules. The model of ternary solutions was used to estimate the potential energy in the molecular pairs of the type N-ylid-protic solvent.

• Solvatochromic effects in electronic absorption spectra of two N-ylids were analyzed.
• Wavenumber in the maximum of the visible electronic absorption band was computed.
• Electric dipole moments of the studied N-ylids in the excited state were estimated.
• Composition of the first solvation shell of the studied N-ylids was established.
• Differences between the energies in molecular pairs ylid-solvent were computed.