Self-assembled coordination complexes from various palladium(II) components and bidentate or polydentate ligands

Palladium(II) has four coordination sites and forms square planar complexes. Discrete self-assemblies are generated by the combination of a variety of palladium(II) components and ligands ranging from bi- to polydentate. The Pd(II) components used are generally of two varieties: cis-protected Pd(II) and unprotected Pd(II). Most common cis-protecting units (X-X) such as ethylenediamine, 2,2′-bipyridine and 1,3-bis(diphenylphosphino)propane and a few other related chelating systems have been exploited for the complexation reactions. The self-assemblies formed are generally represented as [{cis-Pd(X-X)}x(L)y](monoanion)2x and [Pdm(L)n](monoanion)2m when generated from the complexation of a suitable ligand (L) with cis-protected Pd(II) and simple Pd(II) units, respectively. When Pd(solvent)2Cl2 is complexed with ligands, the solvent molecules are replaced with the incoming ligands, leading to complexes in which the trans positions are occupied by the chloride anions.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (52 K)Download as PowerPoint slideHighlights► Self-assembly of a palladium(II) component (M) and a ligand (L) provides (M)x(L)y. ► Self-assembled (M)x(L)y(L′)z are achieved by employing two different ligands. ► cis-protected Pd(II), simple Pd(II) salts and PdCl2, are employed for complexation. ► Bidentate or polydentate ligands are engaged to construct the assemblies. ► A dynamic equilibrium of assemblies is observed in some cases.