title: 13C NMR Spectroscopy of N-Heterocyclic Carbenes Can Selectively Probe σ Donation in Gold(I) Complexes.
abstract: The Dewar-Chatt-Duncanson (DCD) model provides a successful theoretical framework to describe the nature of the chemical bond in transition-metal compounds and is especially useful in structural chemistry and catalysis. However, how to actually measure its constituents (substrate-to-metal donation and metal-to-substrate back-donation) is yet uncertain. Recently, we demonstrated that the DCD components can be neatly disentangled and the π back-donation component put in strict correlation with some experimental observables. In the present work we make a further crucial step forward, showing that, in a large set of charged and neutral N-heterocyclic carbene complexes of gold(I), a specific component of the NMR chemical shift tensor of the carbenic carbon provides a selective measure of the σ donation. This work opens the possibility of 1) to characterize unambiguously the electronic structure of a metal fragment (LAu(I)n+/0in this case) by actually measuring its σ-withdrawing ability, 2) to quickly establish a comparative trend for the ligand trans effect, and 3) to achieve a more rigorous control of the ligand electronic effect, which is a key aspect for the design of new catalysts and metal complexes.
authors.affiliation: Science Division, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA.
authors.forename: Demian
authors.initials: D
authors.lastname: Marchione
authors.affiliation: Theoretical Chemistry, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.|Software for Chemistry and Materials, Theoretical Chemistry, Vrije University, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Izquierdo
authors.affiliation: Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany.
authors.forename: Giovanni
authors.identifier: http://orcid.org/0000-0003-4849-1323
authors.initials: G
authors.lastname: Bistoni
authors.affiliation: Theoretical Chemistry, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.|Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.|Department of Inorganic and Physical Chemistry, University of Ghent, Krijgslaan 281 (S3), 9000, Gent, Belgium.
authors.forename: Remco W A
authors.initials: RW
authors.lastname: Havenith
authors.affiliation: Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Italy.
authors.forename: Alceo
authors.identifier: http://orcid.org/0000-0001-7866-8332
authors.initials: A
authors.lastname: Macchioni
authors.affiliation: Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Italy.
authors.forename: Daniele
authors.identifier: http://orcid.org/0000-0001-7765-1715
authors.initials: D
authors.lastname: Zuccaccia
authors.affiliation: Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Italy.|Istituto di Scienze e Tecnologie Molecolari del CNR (CNR-ISTM), Via Elce di Sotto 8, 06123, Perugia, Italy.
authors.forename: Francesco
authors.identifier: http://orcid.org/0000-0002-1285-0606
authors.initials: F
authors.lastname: Tarantelli
authors.affiliation: Istituto di Scienze e Tecnologie Molecolari del CNR (CNR-ISTM), Via Elce di Sotto 8, 06123, Perugia, Italy.
authors.forename: Leonardo
authors.identifier: http://orcid.org/0000-0002-2888-4990
authors.initials: L
authors.lastname: Belpassi
keywords: N-heterocyclic carbenes; NMR spectroscopy; bond theory; gold