The Syntheses and Electrochemical Studies of a Ferrocene Substituted Diiminopyridine Ligand and Its P, S, Se, and Te Complexes

A new reversible, redox active diiminopyridine ligand
(1Fc) containing pendant ferrocene functionalities was
isolated and fully
characterized. The reaction of 1Fc with chalcogen pseudohalides
of sulfur, selenium, and tellurium yielded the respective N,N′,N″-chelated
chalcogen dications. Phosphorus chemistry proceeded in a related manner
but, in this case, by the direct addition of 1Fc with
PI3 to yield the N,N′,N″-chelated P­(I) cation. These species represent
the first synthesized main group complexes involving a redox active
diiminopyridine ligand containing pendant ferrocenes. Electrochemical
studies of the free ligand shows a reversible two-electron process.
The chelated phosphorus cation, however, displayed three events, the
first being a quasi-reversible two-electron process, involving the
oxidation at the P­(I) center, resulting in a P­(III) cation. The subsequent
reversible one- and two-electron processes arise from the ligand framework
and pendant ferrocenes, respectively.