A triangular palladium(II) supramolecular coordination complex based on 1,4-bis(1H-imidazol-1-yl)benzene and...

The self-assembly of ditopic bis(1H-imidazol-1-yl)benzene ligands (L^H) and the complex (2,2'-bipyridyl-κ²N,N')bis(nitrato-κO)palladium(II) affords the supramolecular coordination complex tris[μ-bis(1H-imidazol-1-yl)benzene-κ²N³:N^3']-triangulo-tris[(2,2'-bipyridyl-κ²N,N')palladium(II)] hexakis(hexafluoridophosphate) acetonitrile heptasolvate, [Pd₃(C₁₀H₈N₂)₃(C₁₂H₁₀N₄)₃](PF₆)₆·7CH₃CN, 2. The structure of 2 was characterized in acetonitrile-d₃ by ¹H/¹³C NMR spectroscopy and a DOSY experiment. The trimeric nature of supramolecular coordination complex 2 in solution was ascertained by cold spray ionization mass spectrometry (CSI-MS) and confirmed in the solid state by X-ray structure analysis. The asymmetric unit of 2 comprises the trimetallic Pd complex, six PF₆^- counter-ions and seven acetonitrile solvent molecules. Moreover, there is one cavity within the unit cell which could contain diethyl ether solvent molecules, as suggested by the crystallization process. The packing is stabilized by weak inter- and intramolecular C-H...N and C-H...F interactions. Interestingly, the crystal structure displays two distinct conformations for the L^H ligand (i.e. syn and anti), with an all-syn-[Pd] coordination mode. This result is in contrast to the solution behaviour, where multiple structures with syn/anti-L^H and syn/anti-[Pd] are a priori possible and expected to be in rapid equilibrium.