The sulfate ligand as a promising “player” in 3d-metal cluster chemistry

The potentiality of the sulfate ligand in the chemistry of polynuclear 3d-metal complexes (clusters) is illustrated through few, representative examples from our own research. A systematic search from the Cambridge Crystallographic Data Base reveals that the SO42- ligand can adopt 16 different bridging coordination modes, being capable of linking 2, 3, 4, 5, 6, 8 or even 10 metal ions. Despite its tremendous structural flexibility, the use of the SO42- ligand in synthetic 3d-metal cluster chemistry has been largely neglected. This report shows that the sulfate ions, in combination with anions of di-2-pyridyl ketone or various 2-pyridyl oximes are versatile ligand “blends” for the synthesis of interesting Ni(II) and Zn(II) clusters with interesting structures and properties. A prognosis for the future is attempted.

Graphical abstractThe SO42- ion can bridge 2, 3, 4, 5, 6, 8 or even 10 metal ions; seven of the 16 crystallographically confirmed ligation modes of the sulfate ligand are shown above. The structural flexibility of the SO42- ligand makes it a promising “player” in 3d-metal cluster chemistry. The synthetic utility of sulfate/organic ligand “blends” in this chemistry is illustrated through examples from our research group.Figure optionsDownload full-size imageDownload as PowerPoint slide