SYNTHESIS AND CHARACTERIZATION OF THE NEW DIAZA FERROCENE MACROCYCLE 1,1'-(2,6-DIAZAHEPTA-1,6-DIENE)FERROCENE AND ITS PARENT AMINE 1,1'-(2,6-DIAZAHEPTANE)FERROCENE

Reaction of ferrocene-1,1'-dicarbaldehyde and propylenediamine yields the Schiff-base derivative 1,1'-(2,6-diazahepta-1,6-diene)ferrocene (1 ), The molecular structure of 1 has been determined by single crystal X-ray analysis. It crystallises in the monoclinic system, space group P2(1)/c, a=13.507(3), b=9.800(2), c=10.086(2) Angstrom, beta=110.81(3) degrees, Z=4 and V=1248.0(5) Angstrom(3). Refinement of the atomic par ameters by least-squares techniques gave a final R factor of 0.074 for 1588 observed reflections having I> 2 sigma(I). Hydrogenation of 1 wi th LiAlH4 results in the parent amine 1,1'-(2,6-diazaheptane)ferrocene (2). The protonation of 2 has been investigated by potentiometry in w ater in the pH range 11-6. At pH lower than 6, 2 is unstable in soluti on. The E-1/2 potential for 2 is pH-dependent (E-1/2(pH 11)=255, E-1/2 (pH 6)=435 mV). A similar behaviour was also observed in THF:water (60 :40 vol./vol.). The electrochemical behaviour for 1 and 2 has also bee n studied in CH2Cl2.