New Polypyridine Ligands Functionalized with Redox-Active Fe(II) Organometallic Fragments

We report in this Communication the isolation and characterization,
including structure determinations, of 2,2‘,6‘,2‘ ‘-terpyridine (2) and
2,2‘-bipyridine (3) ligands bearing two redox-active “(η2-dppe)(η5-C5Me5)FeC⋮C−” moieties grafted to the 5 and 5‘ ‘ positions of
terpy or to the 5 and 5‘ positions of bipy. These “metalloligands”
have been complexed with Ru(II) and Mo(0), providing new
heterotrinuclear complexes displaying intense absorptions around
700 and 600 nm, respectively, for the Fe2Ru/terpy and Fe2Mo/bipy species. In both cases, the Fe(II)/Fe(III) oxidation potentials
of the free ligands became more positive by more than 50 mV
upon complexation.