Synthesis and characterization of a polymetallic supermolecule containing four ruthenium(II)-bipyridine complexes attached to an iron(II) polyimine center

A new polymetallic supermolecule containing four [Ru(bipy)(2)Cl](+) groups attached to the pendant pyridine residues of the bis(2,6-diacetyl-4-methylpyridyliminepyridine ) iron(II) complex has been synthesized. The species exhibits the characteristic MLCT bands of the iron(II)-polyimine and Ru(II)-bipy chromophores at 584 and 486 nm, respectively, and an emission band at 614 nm (at 77 K) ascribed to the decay of the lowest (MLCT)-M-3 state in the [Ru(bipy)(2)Cl](+) group. Based on cyclic voltammetry and spectroelectrochemical measurements, the potentials of the Ru-III/II and Fe-III/II redox couples have been estimated as 1.0 and 1.3 V versus SHE, respectively. A series of reduction waves has been observed below -0.8 V, and ascribed to the successive reduction of the polyimine ligand, generating an iron(II)-diimine product.