X-ray, vibrational spectra and density functional studies on cynacure

The solid-state X-ray diffraction, FT-IR and FT-Raman measurements of cynacure have been performed. Optimized molecular structures and normal vibrations of cynacure and 2-(methylthio)aniline have been calculated in the gas phase at the B3LYP/6-311++G** level. Scaling factors that bring computational gas-phase frequencies in closer agreement with the solid-state experimental data have been calculated for each vibration type. The observed IR and Raman bands of cynacure and 2-(methylthio)aniline have been assigned in the frameworks of the calculated mode frequencies as well as the calculated IR and Raman intensities. The assignments of the normal modes of cynacure have been compared with those of the benzene and 2-(methylthio)aniline modes. The effects of the substitution on the benzene vibrational frequencies have been investigated. 2-(Methylthio)aniline and cynacure both have four stable conformers. The calculated ground-state energetics and vibrational spectra of 2-(methylthio)aniline and cynacure suggest the coexistence of their stable conformers at the room temperature.

► The study investigates the structure and vibrational spectra of 2-(methylthio)aniline and cynacure. ► The study suggests that vibrational spectra of 2-(methylthio)aniline and cynacure both contain signals from their four conformers that are energetically close to each other. ► The study compares vibrational spectra of 2-(methylthio)aniline and cynacure with each other and with the spectra of benzene to reveal substitution effects.