Mono and trinuclear lanthanide complexes of 13-membered tetraaza macrocycle: Synthesis and characterization

The reaction of 1,8-diamino-3,6-diazaoctane and diethyl malonate in dry met hanol yielded a 13-membered macrocycle. Complexes of the type [Ln(tatd)Cl-2 (H2O)(3)]Cl [Ln(III)=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy; tatd = 1, 5, 8, 11s-t etraazacyclotridecane-2,4-dione] have been synthesized by template condensa tion. The complex [La(tatd)Cl-2 (H2O)(3)]Cl in methanol was reacted with la nthanide chlorides to yield the trinuclear complexes of type [2{La(tald)Cl- 2(H2O)(3)} LnCl(3)]Cl-2 [Ln(III) = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy]. The che mical compositions of mono and trinuclear complexes have been established o n the basis of analytical, molar conductance, electrospray (ES) and fast at om bombardment (FAB) mass data. In mononuclear complexes the Ln(3+) ion is encapsulated by four ring nitrogens and in trimetallic complexes the exo-ca rbonyl oxygens of two mononuclear units coordinate to the Ln3+ ions resulti ng in a polyhedron around the lanthanide ions. Thus the macrocycle is bonde d in a tetradentate fashion in the former complexes and hexadentate in the latter. The coordination number nine around the encapsulated Ln(3+) and sev en around the exo-oxygen bonded Ln(3+) ions are established. The symmetry o f the ligand field around the metal ions is indicated from the emission spe ctra.