TY - JOUR

T1 - Impact of fluorination and chlorination on the electronic structure, topology and in-plane ring normal modes of pyridines

AU - Benassi, Enrico

AU - Vaganova, Tamara

AU - Malykhin, Evgenij

AU - Fan, Haiyan

N1 - Funding Information: HF acknowledges the Nazarbayev University small grant 110119FD4542. TV and EM acknowledge support by the Ministry of Science and Higher Education of the Russian Federation (project AAAA-A21-121011490017-5). The authors are grateful to the Siberian Supercomputer Centre of Institute of Computational Mathematics and Mathematical Geophysics (Russian Academy of Sciences, Novosibirsk, Russian Federation) for providing the computational resources; the technical staff of the Institute are also acknowledged for their assistance. The core and computational facilities offered by Nazarbayev University are acknowledged. Publisher Copyright: © 2021 the Owner Societies.

PY - 2021/9/14

Y1 - 2021/9/14

N2 - Seven partially and fully fluorinated/chlorinated pyridines were investigated by means of FT-IR and Raman spectroscopy combined with quantum chemical calculations, mainly aiming to detect how the nature and position of F and Cl substituents affect the in-plane ring normal modes (RNMs) of pyridines in terms of vibrational wavenumbers, force constants, IR intensities and Raman activities. Taking pyridine as the reference, the RNMs and some derived RNMs through coupling with related C-X (X = F, Cl) stretching vibrations were identified on the basis of their composition in terms of internal coordinates. The impact of fluorination and chlorination on these RNMs was also discussed from the perspective of frontier molecular orbitals (MOs), maps of the molecular electrostatic potential (MEP) and the molecular topology. Natural bond orbital (NBO) analysis revealed the consequences of substitutions on the intramolecular charge delocalisation and consequently the ring bond strength. Moreover, the effects of anharmonicity of the potential on vibrational frequencies were presented and discussed.

AB - Seven partially and fully fluorinated/chlorinated pyridines were investigated by means of FT-IR and Raman spectroscopy combined with quantum chemical calculations, mainly aiming to detect how the nature and position of F and Cl substituents affect the in-plane ring normal modes (RNMs) of pyridines in terms of vibrational wavenumbers, force constants, IR intensities and Raman activities. Taking pyridine as the reference, the RNMs and some derived RNMs through coupling with related C-X (X = F, Cl) stretching vibrations were identified on the basis of their composition in terms of internal coordinates. The impact of fluorination and chlorination on these RNMs was also discussed from the perspective of frontier molecular orbitals (MOs), maps of the molecular electrostatic potential (MEP) and the molecular topology. Natural bond orbital (NBO) analysis revealed the consequences of substitutions on the intramolecular charge delocalisation and consequently the ring bond strength. Moreover, the effects of anharmonicity of the potential on vibrational frequencies were presented and discussed.

UR - http://www.scopus.com/inward/record.url?scp=85114357253&partnerID=8YFLogxK

U2 - 10.1039/d1cp02342j

DO - 10.1039/d1cp02342j

M3 - Article

C2 - 34612435

AN - SCOPUS:85114357253

VL - 23

SP - 18958

EP - 18974

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 34

ER -