New insights into chloromethyl-oxirane and chloromethyl-thiirane in liquid and solid phase from low-temperature infrared spectroscopy and ab initio modeling.

A detailed study of the conformational landscape of chloromethyl-oxirane and chloromethyl-thiirane is here reported. The equilibrium of the three different conformers of the two molecules was assessed, using a joint approach of experimental and theoretical methods. High quality infrared spectroscopy measurements of the liquid and of the crystalline phases were interpreted with the aid of ab initio Molecular Dynamics (AIMD) simulations, anharmonic frequencies and free energy calculations, obtaining a very good reproduction of the experimental data. The modulation of the conformational equilibrium upon the addition of polar and non-polar solvents was computationally evaluated and results found a confirmation in experimental measures.