Single-Molecule Activation and Quantification of Mechanically Triggered Palladium-Carbene Bond Dissociation.
Anton O RazgoniaevLogan M GlasstetterTatiana B KouznetsovaKacey C HallMatías HorstStephen L CraigKatherine J FranzPublished in: Journal of the American Chemical Society (2021)
Metal-complexed N-heterocyclic carbene (NHC) mechanophores are latent reactants and catalysts for a range of mechanically driven chemical responses, but mechanochemical scission of the metal-NHC bond has not been experimentally characterized. Here we report the single-molecule force spectroscopy of ligand dissociation from a pincer NHC-pyridine-NHC Pd(II) complex. The force-coupled rate constant for ligand dissociation reaches 50 s-1 at forces of approximately 930 pN. Experimental and computational observations support a dissociative, rather than associative, mechanism of ligand displacement, with rate-limiting scission of the Pd-NHC bond followed by rapid dissociation of the pyridine moiety from Pd.