INTERACTION OF NEUTRAL AND ANIONIC O-DONOR ORGANIC-LIGANDS WITH EUROPIUM(III) IN THE MACROCYCLIC COMPLEX [EU(CH3COO)2(C22H26N6)]CL4H2O AND CRYSTAL-STRUCTURE OF [EU(CH3COO)2(C22H26N6)](CH3COO)9H2O

The interaction of the paramagnetic complex [Eu(CH3COO)2L]Cl.4H2O, where L is the six N-donor macrocyclic ligand C22H26N6, with a series of organic substrates having potential O-donor atoms has been investigated. The H-1 NMR resonances of anionic or acidic substrates were greatly shifted in the presence of the europium complex, whereas those of uncharged substrates remained essentially unchanged. The 5D0 --> F-7(2) emission of the europium complex was considerably enhanced in the presence of certain heteroaromatic carboxylates; new complexes of the formula [Eu(RCOO)2L]Cl.nH2O, where R is -C6H5, -C4H3O,-C4H3S,-C4H3NH or -C5H4N and n = 2-4, were isolated in the solid state. The crystal and molecular structure of the triacetate, [Eu(CH3COO)2L](CH3COO).9H2O, was established by single-crystal X-ray crystallography. The structure is ionic, with a 10-coordinate europium(III) linked to the six N-donor atoms of the macrocyclic ligand and to two bidentate chelating acetates situated on opposite sides of the macrocycle. An ionic acetate and a network of hydrogen-bonded H2O molecules (nine per complex unit) completed the crystal lattice.