The first example of an asymmetrical μ-oxo bridged dinuclear iron complex with a terpyridine ligand

The reaction of Fe(III) ions with a 6,6′′-dimethyl-2,2′:6′,2′′-terpyridine ligand L in the presence of chlorides and independent of conditions results in the formation of μ-oxo bridged dinuclear [FeLCl(μ-O)FeCl3] (1) and the mononuclear complex [FeLCl2] (2). X-ray crystallographic analysis revealed the unsymmetrical character of the oxo anion ligand that connects two distinct metallic centers: one comprising a tridentate terpyridine ligand in a meridional coordination mode and one chloride N3FeClO, and the second exhibiting the well-known OFeCl3 moiety. The complex undergoes a quasi-reversible oxidation/reduction process with a color change from yellow to colorless.