X-ray Diffraction and 1H NMR in Solution: Structural Determination of Lanthanide Complexes of a Py2N6Ac4 Ligand

Complexes between the Py2N6Ac4 (H4L) ligand containing four carboxylate pendant arms and trivalent lanthanide ions have been synthesized, and structural studies have been made both in the solid state and aqueous solution. The crystal structures of the La, Ce, Sm, Tb, Dy, Ho, Er, Tm, and Lu complexes, with chemical formulas [LaH2L](NO3)·3H2O (1), [Ce4L2](NO3)4·30H2O (2), [SmHL]·EtOH·3H2O (5), [TbHL]·EtOH·3H2O (8), [DyHL]·2EtOH·2H2O (9), [HoHL]·3H2O (10), [ErHL]·EtOH·3H2O (11) [TmHL]·EtOH·3H2O (12), and [LuHL]·3H2O (14), have been determined by single-crystal X-ray crystallography. In the solid state, the complexes of the lighter lanthanide ions La3+−Dy3+ show a 10-coordinated geometry close to a distorted bicapped antiprism, where the carboxylate pendants are situated alternatively above and below the best plane that contains the nitrogen donor atoms. The complexes of the heavier ions, Ho3+−Lu3+, have a 9-coordinated geometry close to distorted tricapped trigonal prism, with one of the pendant carboxylate ...