Electronic and NMR properties of meso-monosubstituted ferrocenylporphyrin: evidence of pi-conjugation between porphyrin and ferrocene

Abstract

The reaction of dipyrrylmethane with an equimolar mixture of ferrocenecarboxaldehyde and benzaldehyde in dry acetonitrile in the presence of a catalytic amount of trichloroacetic acid leads to the formation of 5-ferrocenyl-15-phenyl-2,8,12,18-tetraethyl-3,7,13, 17-tetramethylporphyrin (1) with a yield of 27%. The metallation of 1 with Zn(OAc)(2). 2H(2)O and MnCl2. 4H(2)O gives Zn(.)1 and MnCl(.)1, respectively. Cyclic voltammograms of 1, Zn(.)1 and MnCl(.)1 show reversible one-electron oxidation processes for the oxidation of ferrocene at 0.29. 0.22, and 0.37 V, respectively. Variable temperature H-1 NMR spectra of 1 in toluene-d(s) show two distinct singlets of equal intensities and line widths for NH protons. From the plot of In (k/T) versus 1/T according to the Eyring equation, gave straight line with Delta G(double dagger) = 51 kJ mol(-1). (C) 2000 Elsevier Science Ltd. All rights reserved.