Lewis acid behavior of SF4: synthesis, characterization, and computational study of adducts of SF4 with pyridine and pyridine derivatives

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Chaudhary, Praveen
Goettel, James T.
Mercier, Hélène P. A.
Sowlati-Hashjin, Shahin
Hazendonk, Paul
Gerken, Michael
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Sulfur tetrafluoride was shown to act as a Lewis acid towards organic nitrogen-bases, such as pyridine, 2,6-dimethylpyridine, 4-methylpyridine, and 4-dimethylaminopyridine. The SF4·NC5H5, SF4·2,6-NC5H3(CH3)2, SF4·4-NC5H4(CH3), and SF4·4-NC5H4N(CH3)2 adducts can be isolated as solids that are stable below –45 °C. The Lewis acid-base adducts were characterized by low temperature Raman spectroscopy and the vibrational bands were fully assigned with the aid of density-functional-theory (DFT) calculations. The electronic structures obtained from the DFT calculations were analyzed by the quantum theory of atoms in molecules (QTAIM). The crystal structures of SF4·NC5H5, SF4·4-NC5H4(CH3), and SF4·4-NC5H4N(CH3)2 revealed weak S---N dative bonds with nitrogen coordinating in the equatorial position of SF4. Based on the QTAIM analysis, the non-bonded valence shell charge concentration on sulfur, which represents the lone pair, is only slightly distorted by the weak dative S---N bond. No evidence for adducts between quinoline or isoquinoline with SF4 was found by low-temperature Raman spectroscopy.
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Fluorine , Lewis acids and bases , Raman spectroscopy , Structure eludication , Sulfur
Chaudhary, P., Goettel, J. T., Mercier, H. P. A., Sowlati-Hashjin, S., Hazendonk, P., & Gerken, M. (2015). Lewis acid behavior of SF4: Synthesis, characterization, and computational study of adducts of SF4 with pyridine and pyridine derivatives. Chemistry- A European Journal, 21(16), 6247-6256. https://doi.org/10.1002/chem.201406359