Interactions of weakly coordinating anions with tripalladium sandwich complexes

An understanding of the interaction of weakly coordinating ligands with zero-valent palladium complexes is of importance to understanding the potential catalytic mechanisms and properties of these complexes. We have used a combination of multi-nuclei NMR, microanalysis and single crystal X-ray diffraction to characterize a series of tripalladium ditropylium sandwich complexes that possess one or more triflate [CF3SO3]− ligands. The influence of the strong electronic effects on the triflate ligand cause a significant change in the internal bond lengths and angles of the complexes which are coupled to systematic shifts of the tropylium 1H and 13C resonances in the NMR spectra. The use of the Advanced Light Source (ALS) permitted crystallographic characterization of only the third example of a complex containing a Pd–FBF3 bond.

Graphical abstractA series of tripalladium sandwich complexes with weakly coordination anions were prepared and characterized by multinuclear NMR and single crystal X-ray diffraction studies. This related series of complexes includes only the third crystallographically characterized palladium complex having bridging triflate ligands and a rare example of a crystallographically characterized palladium complex with a direct Pd–FBF3 bond.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Palladium sandwich complexes with weakly-coordinating anions are reported. ► Triflate ligands may form monomeric or polymeric structures. ► The vacant coordination site may incorporate a range of ligands including H2O and BF4.