Substituent effects on the electrochemical behaviour of iron(II) in Schiff bases derived from ferrocene and their cyclopalladated compounds

Cyclic voltammetries of ferrocenylimines [(eta(5)-C5H5)Fe{(eta(5)-C5H4)-C(R(1))=N-R(2)}] (1-3) and [(eta(5)-C5H5)Fe{(eta(5)-C5H4)-(CH2)n-N=CH(C6H(5-x)R(x)(3))}] (4, 5), and bis(ferrocenyl)imine [(eta(5)-C5H5)Fe{(eta(5)-C5H4)-(CH2)(n)-N=C(R(4))(eta(5)-C5H4)}Fe(eta(5)-C5H5)] (6) are reported. The comparison of the half-wave potentials (E(1/2)) shows that the liability of iron(II) to undergo oxidation on the nature of the substituents. For their mono- and dinuclear cyclopalladated compounds, [Pd(C N)Cl(L)] and [Pd(C N)(mu-Cl)] 2, the E(1/2) values reveal that the formation of a sigma(Pd-C(sp(2), ferrocene)) bond favours the oxidation of the ferrocenyl moiety, while for compounds with a sigma(Pd-C(sp(2), phenyl)) bond the trend is the opposite.