Gold(III) complexes with monodentate coordinated diazines: An evidence for strong electron-withdrawing effect of Au(III) ion

Gold(III) complexes containing heterocyclic diazines as ligands, [AuCl3(az)], have been synthesized. Regardless of different stoichiometric ratio of the starting [AuCl4]− complex and diazine ligand, only gold(III) complexes with monodentatly coordinated diazines have been isolated and characterized by NMR and X-ray diffraction techniques. The [AuCl3(az)] complexes with stronger heteroaromatic bases, pyridazine and pyrimidine, form isostructural crystals in which the molecules are engaged in columnar Au⋯Cl interactions and π⋯π stacking within the columns, and utilize the uncoordinated nitrogen atom as an acceptor of C–H⋯N hydrogen bond. On the other hand, the [AuCl3(pz)] complex containing the weakest pyrazine base does not engage its uncoordinated nitrogen atom in intermolecular interactions.

Graphical abstractRegardless of different stoichiometric ratio of the substrates, reactions of gold(III) with isomeric diazines invariably lead to the formation of mononuclear [AuCl3(diazine)] complexes which have been fully structurally characterized.Figure optionsDownload full-size imageDownload as PowerPoint slide