title: Selectively measuring π back-donation in gold(I) complexes by NMR spectroscopy.
abstract: Even though the Dewar-Chatt-Duncanson model has been successfully used by chemists since the 1950s, no experimental methodology is yet known to unambiguously estimate the constituents (donation and back-donation) of a metal-ligand interaction. It is demonstrated here that one of these components, the metal-to-ligand π back-donation, can be effectively probed by NMR measurements aimed at determining the rotational barrier of a C-N bond (ΔHr (≠) ) of a nitrogen acyclic carbene ligand. A large series of gold(I) complexes have been synthesized and analyzed, and it was found that the above experimental observables show an accurate correlation with back-donation, as defined theoretically by the appropriate charge displacement originated upon bond formation. The proposed method is potentially of wide applicability for analyzing the ligand effect in metal catalysts and guiding their design.
authors.affiliation: Istituto di Scienze e Tecnologie Molecolari del CNR (CNR-ISTM), Via Elce di Sotto 8, 06123, Perugia (Italy).
authors.forename: Gianluca
authors.initials: G
authors.lastname: Ciancaleoni
authors.forename: Luca
authors.initials: L
authors.lastname: Biasiolo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bistoni
authors.forename: Alceo
authors.initials: A
authors.lastname: Macchioni
authors.forename: Francesco
authors.initials: F
authors.lastname: Tarantelli
authors.forename: Daniele
authors.initials: D
authors.lastname: Zuccaccia
authors.forename: Leonardo
authors.initials: L
authors.lastname: Belpassi
mesh_terms: D002244:Carbon / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D056831:Coordination Complexes; D002244:Carbon; D006046:Gold; D009584:Nitrogen
keywords: NMR spectroscopy; bond theory; density functional calculations; gold; ligands