BINUCLEAR COMPLEXES OF A NEW HEXADENTATE MACROCYCLIC LIGAND - THE CRYSTAL AND MOLECULAR-STRUCTURE OF [LCU2(CH3CO2)2](CLO4)2.5H2O

The 30-membered hexaaza macrocylic ligand, L (L = iaconta-1(31),13(33) ,14,16(34),28(32),29-hexaene), is capable of forming binuclear complex es with the divalent transition metal ions Ni, Cu and Zn. The two meta l ions are bound by the two dipropylenetriamine units of the macrocycl e. Extra coordination sites on the metal ions can be occupied by exoge nous ligands such as acetate, chloride and thiocyanate. The crystal st ructure of one of the di-copper complexes is described: [LCu2(CH3CO2)2 ](ClO4)2.5H2O crystallizes in the monoclinic space group P2(1)/c (No. 14), with a = 9.369(2), b = 17.644(3), c = 27.466(3) angstrom, beta = 92.90(1)-degrees, U = 4534.7 angstrom3 and Z = 4. The Cu1 ... Cu2 sepa ration is 8.40(3) angstrom. The access for potential exogenous bridgin g ligands, to the cavity between the copper ions, is somewhat restrict ed by the two phenyl units of the macrocycle which appear almost paral lel in the structure. The redox potential of the couple L(Cu2+)2/L(Cu)2, recorded by cyclic voltammetry for the chloride adduct, [LCu2Cl2]C l2.5H2O, is -0.061 V versus SCE in DMF.