Impact of fluorination and chlorination on the electronic structure, topology and in-plane ring normal modes of pyridines
Benassi E. Vaganova T. Malykhin E. Fan H.
14 September 2021Royal Society of Chemistry
Physical Chemistry Chemical Physics
2021#23Issue 3418958 - 18974 pp.
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.
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Novosibirsk State University, Novosibirsk, 630090, Russian Federation
Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, Novosibirsk, 630090, Russian Federation
Department of Chemistry, School of Sciences and Humanities, Nazarbayev University, Nursultan, 010000, Kazakhstan
Novosibirsk State University
Vorozhtsov Novosibirsk Institute of Organic Chemistry
Department of Chemistry
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