X-RAY CRYSTAL-STRUCTURES AND NUCLEAR-MAGNETIC-RESONANCE SPECTRA OF MACROCYCLIC COMPLEXES OF NEODYMIUM(III) AND EUROPIUM(III)

The compounds of formula [M(CH3COO)2LI]Cl·4H2O, in which M is neo-dymium(III) or europium(III) and LI is a six-nitrogen-donor macrocyclic ligand (C22H26N6), have been investigated by single crystal X-ray diffraction, thermogravimetric analysis and nuclear magnetic resonance spectroscopy. The two compounds are isostructural and crystallize in the triclinic system, space group P1. The complex cations present in the crystal lattice consist of a 10-coordinate metal centre linked to the six nitrogen-donor atoms of the macrocyclic ligand and to two bidentate chelating acetates, situated on opposite sides of the macrocycle and staggered by approximately 90°; an ionic chloride balances the residual metal charge. The paramagnetic-shifted NMR spectra of the complexes were measured in various solvents, and confirm that the metal-macrocycle moieties remain undissociated. Also, the spectra depend on the counterions, showing that, on average, at least one of the labile acetate ligands is bound to the metal ion even in aqueous solution. © 1990.