Breaking the metal-carbene bond

Congrats to Anton, Logan, Tatiana, and team!  Their paper, “Single-molecule activation and quantification of mechanically-triggered palladium-carbene bond dissociation,” has been accepted for publication at JACS. Metal-complexed N-heterocyclic carbene (NHC) mechanophores are latent reactants and catalysts for a range of mechanically-driven chemical responses, and this work reports 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.