Oligo- and polymeric PdII and PtII using pyridyl carboxylate spacers for topology control

An array of Pd-II and Pt-II supramolecular assemblies have been constructed using pyridyl carboxylates as spacers and phosphines [(C5H4PPh2)(2)Fe (dppf) and PPh3)] as supporting ligands. Different molecular topologies such as squares, triangles, rectangles, and polymers can be controlled by the spatial and directional character of the spacer. A change of the denticity of the phosphine does not affect the topological outcome. Significant differences, however, are observed for the congeneric analogues, with Pd-II showing a more pronounced tendency toward coordination polymer formation and its attached carboxyl a higher affinity toward Ag+. The ability of these assemblies to capture cations, such as Na+ in [Pt3Na(3-NC5H4CO2)(3)(OTf)(3)(PPh3)(6)](+) through hydrogen bonding or Ag+ in [PdAg(2-NC5H4CO2)(OTf)(2)(dppf)] through dative bonding, is described and compared. All of the complexes are structurally characterized by single-crystal X-ray crystallography.