A number of cationic and neutral η3-furfuryl complexes of palladium and platinum were prepared, including one with a ligand derived from fructose, 5-chloromethylfurfural. The complexes were studied by variable-temperature and heteronuclear correlation NMR spectroscopy, as well as single-crystal X-ray crystallography. Analogous η3-thienyl complexes could be prepared and detected in solution by NMR, but could not be isolated due to facile decomposition.

Five-membered heterocyclic analogues of the well-known η3-allyl and η3-benzyl ligands, e.g., η3-thienyl and η3-furfuryl, have been proposed as catalytic intermediates, yet are poorly understood and have never been structurally confirmed. Herein we characterize an η3-furfuryl complex by multinuclear NMR spectroscopy and crystallography and offer a computational survey of allyl and allyl-like ligands. Crystallographically and computationally, we show that the η3-furfuryl ligand may bind more strongly than corresponding η3-benzyl ligands and is plausible as a catalytic intermediate.