Reaction of ferrocene-1,1′-dicarbaldehyde and ethane-1,2-diamine yielded the Schiff-base derivative 2,5,19,22-tetraaza[6.6](1,1′)ferrocenophane-1,5-diene, 1 the molecular structure of which has been determined by single-crystal X-ray analysis. Hydrogenation of 1 with LiAlH4 resulted in the corresponding amine 2,5,19,22-tetraaza-[6.6](1,1′)ferrocenophane 2 which was characterised crystallographically. The protonation behaviour of 2 (denoted as L) and its complex formation with copper(II), nickel(II) and zinc(II) has been studied by potentiometric titrations in tetrahydrofuran-water (70:30 v/v) (0.1 mol dm-3 NBu4ClO4, 25°C). The complexes [M(HL)]3+, [ML]2+, [M(OH)]+ and [ML(OH)2] are formed. An electrochemical study of compound 2 has also been performed under the same conditions at which the potentiometry was carried out and the pKa values for the mixed-valence FeIIFeIII and oxidised FeIIIFeIII species determined by fitting the curve of E1/2 versus pH. From those data the Pourbaix diagram of the redox-active 2 has been calculated. Compound 2 can be considered as a selective electrochemical sensor for copper(II).
|Number of pages||9|
|Journal||Journal of the Chemical Society - Dalton Transactions|
|Publication status||Published - 7 Feb 1996|
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