Catalytic and Stoichiometric Synthesis of Ferrocene-Containing Polyazamacrocycles and Chelating Bidentate Nitrogen Ligands

A series of ferrocene-containing chelating bidentate nitrogen ligands (1 & 2) and polyazamacrocycles (3 & 4) were prepared in high yields from the reaction of ferrocenecarboxaldehydes with corresponding diamines under various catalytic and stoichiometric reaction conditions. The stoichiometric condensation to form Schiff bases required the presence of MgSO₄in the reaction mixture as a water-absorbent. Employment of cyclic diamines such as 1,2-diaminocyclohexane and p-phenylenediamine in the reaction with 1,1'-ferrocenedicarboxaldehyde resulted in the formation of polymers in stead of the expected macrocycles. All these compounds were characterized by microanalytical and spectroscopic techniques. In one case, the structure of 3a was confirmed by X-ray crystallography.