REACTION OF FERROCENECARBALDEHYDE WITH O-PHENYLENEDIAMINE - CRYSTAL-STRUCTURE OF N-FERROCENYLMETHYL-2-FERROCENYL-BENZIMIDAZOLE

The reaction of ferrocenecarbaldehyde with o-phenylenediamine in the p resence of p-toluenesulphonic acid results in the synthesis of N-ferro cenylmethyl-2-ferrocenyl-benzimidazole 1, and 2-ferrocenyl-benzimidazo le, 2. The molecular structure of 1 has been determined by single crys tal X-ray analysis. It crystallises in the triclinic system, space gro up P ($) over bar 1, a = 10.069(7), b = 13.625(8), c = 9.314(7) Angstr om, alpha = 92.75(5)degrees, beta = 104.68(6)degrees, gamma = 95.43(6) degrees; V = 1227(1) Angstrom(3), Z = 2. An electrochemical study of 1 and 2 in dichloromethane:methanol (10:1) has been carried out. 2 show s a reversible oxidation process at Ep(a) = 535 mV. The addition of HC l (1 equiv.) switches the oxidation potential giving a new wave at Ep( a) = 800 mV. 1 shows a reversible 2 e oxidation process at Ep(a) = 558 mV which is split into two different waves when 1 equiv. of HCl is ad ded. The switching process is reversible for 1 and 2 and addition of b ase (KOH) leads to the former oxidation potential.