RT info:eu-repo/semantics/article T1 How aromatic fluorination exchanges the interaction role of pyridine with carbonyl compounds: The formaldehyde adduct A1 López Alonso, Juan Carlos A1 Macario Farto, Alberto A1 Maris, Assimo A1 Alkorta, Ibon A1 Blanco Rodríguez, Susana K1 Aromatic fluorination K1 Pyridine K1 Carbonyl compounds K1 Pentafluoropyridine K1 Formaldehyde K1 23 Química AB The rotational spectrum of the weakly bound complexpentafluoropyridineꞏꞏꞏformaldehyde has been investigated usingFourier transform microwave spectroscopy. From the analysis of therotational parameters of the parent species and of the 13C and 15Nisotopologues, the structural arrangement of the adduct has beenunambiguously established. The full ring fluorination of pyridine has adramatic effect on its binding properties: It alters the electron densitydistribution at the π-cloud of pyridine creating a π-hole and changingits electron donor-acceptor capabilities. In the complex, formaldehydelies above the aromatic ring with one of the oxygen lone pairs, asconventionally envisaged, pointing toward its centre. This lonepairꞏꞏꞏπ-hole interaction, reinforced by a weak C-HꞏꞏꞏN interaction,indicates an exchange of the electron-acceptor roles of bothmolecules when compared to the pyridineꞏꞏꞏformaldehyde adduct.Tunnelling doublets due to the internal rotation of formaldehyde havealso been observed and analysed leading to a discussion on thecompetition between lone pairꞏꞏꞏπ-hole and π ꞏꞏꞏπ staking interactions. PB Wiley SN 0947-6539 YR 2021 FD 2021 LK https://uvadoc.uva.es/handle/10324/48998 UL https://uvadoc.uva.es/handle/10324/48998 LA eng NO Chemistry – A European Journal, 2021, vol. 27, n. 55, p.13870 –13878 NO Producción Científica DS UVaDOC RD 26-abr-2024