Preparation and electrochemical study of an iron(II) complex of a pentadentate planar macrocyclic ligand

The macrocycle L, prepared by template condensation of bis-6,6 "-(alpha-methylhydrazino)-4'-phenyl-2,2':6 ",2'-terpyridine with glyoxal, forms a stable crystalline complex of (FeI)-I-I, [Fe(L)(H2O)(2)][PF6](2), which has been used as a starting material for electrochemical studies on a series of seven coordinate (FeI)-I-I complexes [Fe(L)X-2](2+) (X = pyridine, 4-cyanopyridine, 4-aminopyridine, 4-dimethylaminopyridine, thiophene, imidazole, 2-methylimidazole or 1,2-dimethylimidazole). Cyclic voltammetry of the aquo complex in MeCN shows three reversible one electron redox waves in the range -0.35-1.70 V versus Ag/AgBF4 reference electrode.