Flash Communication:Pd₂Zn₂ Clusters from the Reduction of Palladium(II)Dichloride Precursors with Metallic Zinc

We report the synthesis and solid-state characterization of two unusual Pd₂Zn₂ clusters formed from the partial reduction of [PdL₂Cl₂] precursors (L₂ = dcpe or dppe) with metallic zinc. The new clusters have been characterized by single crystal X-ray diffraction and contain a Pd₂Zn₂Cl₃ core capped by two chelating phosphine ligands with Zn in the formal +1.5 oxidation state. While they possess a near tetrahedral arrangement of metal ions, calculations and bonding analysis (NBO, AIM) suggest that there is limited Zn- - -Zn bonding in these species. Characterization in the solution state is suggestive of dynamic behavior on dissolution, with both diamagnetic and paramagnetic species observed by NMR and EPR spectroscopy. One of these Pd₂Zn₂ clusters was shown to be an effective precursor for the homocoupling of an aryl bromide.