N-Benzylethylenediamine and dibenzoylmethane (1,3-diphenyl-1,3-propanedione) condense in stoichiometric ratio 1:1 by direct reaction giving the corresponding Schiff monobase; however, this reaction takes place in a significant yield only under very specific conditions due to the low reactivity of dibenzoylmethane (assigned to electronic and steric factors). The neutral bis-chelate of Ni(II) with the deprotonated ligand can readily be prepared in aqueous methanol. Condensation between the diamine and the β-diketone has also been attempted by template reaction assisted by the same metal ion yielding only new mixed complexes of these ligands but without Schiff base condensation. As in the case of direct reaction of the amine with the β-diketone, it seems that template formation of the Schiff base is made difficult by electronic and steric limitations of dibenzoylmethane.

Post time: Oct-14-2021