SYNTHESIS, CHARACTERIZATION, AND CRYSTAL-STRUCTURE OF COMPLEXES OF LANTHANIDE PICRATES WITH N,N,N',N'-TETRAPHENYL-3,6-DIOXAOCTANEDIAMIDE

Lanthanide picrate complexes with the ligand N,N,N',N'-tetraphenyl-3,6 -dioxaoctanediamide (tdd): [Ln(Pic)(3)(tdd)] (Ln = La, Nd, Eu, Tb, Er) have been prepared in a nonaqueous medium and characterized by elemen tal analysis, conductivity measurements, IR, and H-1-NMR spectra. The crystal structures of the complexes for Ln = Nd and Er were determined . The early lanthanide, Nd-III, crystallizes as the nona-coordinate co mplex [Nd(Pic)(3)(tdd)]. 2CH(3)CN in the monoclinic space group P2(1)/ n with a = 11.384(2), b = 18.805(4), c = 27.526(5) Angstrom, beta = 99 .41(1)degrees, V = 5832(2) Angstrom(3), and D-c, = 1.58 g cm(-3) for Z = 4. The structure was refined to R = 0.0505, based on 4772 observed reflections. The late lanthanide, Er-III, forms an octa-coordinate com plex [Er(Pic)(3)(tdd)]; crystals are triclinic, <P(1)over bar>, with a = 12.449(2), b = 17.065(1), c = 26.243(4) Angstrom, alpha = 72.12(1), beta = 87.86(1), gamma = 84.60(1)degrees, V = 5282(1) Angstrom(3), an d D-c = 1.68 g cm(-3) for Z = 4. The structure was refined to R = 0.04 69, based on 10666 observed reflections. The results reveal that tdd f orms a ring-like structure with its four O-atoms, coordinating to the metal ions as multidentate ligand, together with one O-atom of the bid entate picrate. The structure of the complexes is greatly affected by the ionic radius due to participation of the picrates in coordination.