Synthesis and characterization of mono and trinuclear lanthanide (III) complexes of 12-membered tetraaza macrocycle

The reaction of triethylene tetraamine and diethyl oxalate yield a 12-membe red macrocycle. The complexes [Ln(tadd)Cl-2(H2O)(2)]Cl (Ln(III)= La, Pr, Nd , Sm, Eu, Gd, Tb and Dy; tadd = 1,4,7,10-tetraazncyclo dodeccne-2, 3-dione) have been synthesized by template reaction of the lanthanide ion. The comp lex [La(tadd)Cl-2(H2O)(2)]Cl reacts with lanthanide chlorides to yield the complexes of type [2(La(tadd)Cl-2(H2O)Cl-2)LnCl(3)(H2O)]Cl-2. The chemical compositions of both the mono and trimetallic complexes have been establish ed from analytical, molar conductance and FAB mass data It is observed that the macrocycle is bonded in tetrakis fashion in the former complexes and h exakis in the latter. The coordination number eight around the encapsulated metal ions and nine around the exocyclic oxygen bonded metal ions are esta blished from IR and electronic spectra The symmetry of the ligand field aro und the metal ions is indicated from the emission spectra.