Selectively Measuring π Back‐Donation in Gold(I) Complexes by NMR Spectroscopy |
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| Authors: | Dr Gianluca Ciancaleoni Luca Biasiolo Giovanni Bistoni Prof Alceo Macchioni Prof Francesco Tarantelli Dr Daniele Zuccaccia Dr Leonardo Belpassi |
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| Affiliation: | 1. Istituto di Scienze e Tecnologie Molecolari del CNR (CNR‐ISTM), Via Elce di Sotto?8, 06123, Perugia (Italy);2. Dipartimento di Chimica, Fisica e Ambiente, Universita' di Udine, Via Cotonificio?108, 33100, Udine (Italy);3. Dipartimento di Chimica, Biologia e Biotecnologie, Universita' di Perugia, Via Elece di Sotto?8, 06123, Perugia (Italy) |
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| 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. |
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| Keywords: | bond theory density functional calculations gold ligands NMR spectroscopy |
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