title: Four-Component Relativistic DFT Calculations of (13)C Chemical Shifts of Halogenated Natural Substances.
abstract: We have calculated the (13)C NMR chemical shifts of a large ensemble of halogenated organic molecules (81 molecules for a total of 250 experimental (13)C NMR data at four different levels of theory), ranging from small rigid organic compounds, used to benchmark the performance of various levels of theory, to natural substances of marine origin with conformational degrees of freedom. Carbon atoms bonded to heavy halogen atoms, particularly bromine and iodine, are known to be rather challenging when it comes to the prediction of their chemical shifts by quantum methods, due to relativistic effects. In this paper, we have applied the state-of-the-art four-component relativistic density functional theory for the prediction of such NMR properties and compared the performance with two-component and nonrelativistic methods. Our results highlight the necessity to include relativistic corrections within a four-component description for the most accurate prediction of the NMR properties of halogenated organic substances.
authors.affiliation: Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi, 20-90123, Palermo (Italy).|Consorzio Interuniversitario di Ricerca in Chimica dei Metalli nei Sistemi Biologici (C.I.R.C.M.S.B.), Unità Locale di Palermo, Parco d'Orleans II, Viale delle Scienze, Ed. 17-90128 Palermo (Italy).
authors.forename: Girolamo
authors.initials: G
authors.lastname: Casella
authors.affiliation: Dipartimento di Scienze Chimiche (DiSC), Università di Padova, Via Marzolo, 1-35131, Padova (Italy).
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bagno
authors.affiliation: Centre for Theoretical and Computational Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø (Norway).
authors.forename: Stanislav
authors.initials: S
authors.lastname: Komorovsky
authors.affiliation: Centre for Theoretical and Computational Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø (Norway).
authors.forename: Michal
authors.initials: M
authors.lastname: Repisky
authors.affiliation: CNR-Istituto per la Tecnologia delle Membrane (ITM-CNR), Unità di Padova, Via Marzolo, 1-35131, Padova (Italy). giacomo.saielli@unipd.it.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Saielli
keywords: NMR spectroscopy; density functional calculations; halogens; natural products; organohalides