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

O Palumbo; A Paolone; M Campetella; F Ramondo; F Cappelluti; L Gontrani

doi:10.1016/j.saa.2020.119061

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

Spectrochim Acta A Mol Biomol Spectrosc. 2021 Feb 15:247:119061. doi: 10.1016/j.saa.2020.119061. Epub 2020 Oct 9.

Authors

O Palumbo¹, A Paolone¹, M Campetella², F Ramondo², F Cappelluti³, L Gontrani⁴

Affiliations

¹ CNR-ISC, UOS La Sapienza, P. le A. Moro 5, 00185 Roma, Italy.
² Dipartimento di Chimica, Università degli Studi di Roma, P. le Aldo Moro 5, 00185 Roma, Italy.
³ Dipartimento di Ingegneria e Scienza dell'Informazione e Matematica, Università dell'Aquila, Via Vetoio 5, Coppito, 67100 L'Aquila, Italy. Electronic address: francesco.cappelluti@graduate.univaq.it.
⁴ Dipartimento di Chimica, Università degli Studi di Roma, P. le Aldo Moro 5, 00185 Roma, Italy; Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata", Viale degli ingegneri, I-00133 Roma, Italy. Electronic address: lorenzo.gontrani@uniroma2.it.

PMID: 33091738
DOI: 10.1016/j.saa.2020.119061

Abstract

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.

Keywords: Ab initio molecular dynamics; Chloromethyl-oxirane; Conformational equilibrium; Free energy ab initio calculations; Infrared spectroscopy; Low-temperature IR; Solvent effects; Thiirane.