Oligo- and polymeric Pd(II) and Pt(II) 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)2Fe (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.