DIRECTED SYNTHESES AND STRUCTURAL STUDIES OF MONONUCLEAR COPPER(II) AND HETERODINUCLEAR COPPER(II)-IRON(III) COMPLEXES FROM THE SAME UNSYMMETRICAL DINUCLEATING LIGAND

Mononuclear copper(rr) [Cu(H3L)(O2CMe)]BPh4 1 and heterodinuclear copp er(II)-iron(III) [FeCuL(mu OEt)]ClO4 2 complexes from the same dinucle ating ligand H3L have been prepared and isolated methyl-6-[bis(2-pyrid ylmethyl)aminomethyl]phenol}. The crystal structure of the mononuclear complex I demonstrated the site-directed complexation with H3L. For t he heterodinuclear complex 2 the crystal structure reveals that the co pper and iron atoms are bridged by the central phenoxo moiety and by a n exogenous ethoxo group. In addition this structure showed that the i ron atom is five-co-ordinated. Temperature-dependent magnetic suscepti bility measurements revealed an antiferromagnetic interaction (ca. J=- 58.1 cm(-1)) between the copper and iron atoms in 2. Cyclic voltammogr ams in dichloromethane vs. Ag-AgNO3 revealed a quasi-reversible redox behaviour for Cu-II-Cu-I in 1 and 2 (E-1/2=-0.77 and -0.74 V respectiv ely). The reduction of Fe-III in 2 is irreversible with E-pc=-1.69 V. The (CuFeIII)-Fe-I complex is thermodynamically stable towards comprop ortionation.