Dinuclear lanthanide(III) complexes with large-bite Schiff bases derived from 2,6-diformyl-4-chlorophenol and hydrazides: Synthesis, structural characterization and spectroscopic studies

Two Schiff bases (H3L1 and H5L2), derived from 2,6-diformyl-4-chlorophenol and hydrazides, and their complexes with some lanthanides (Y, La, Nd, Sm, Dy and Er) have been synthesized. These compounds have been characterized by means of elemental analysis, UV–Vis spectroscopy, IR spectroscopy, 1H and 13C NMR (for the organic ligands), molar conductance and room temperature magnetic measurements. Single crystal X-ray analysis of the two complexes [La2(H2L1)3(C2H5OH)2]·(Cl)·(NO3)2·((CH3)2CO)2·(H2O)2 (1) and [Er2(H4L2)3]·(SCN)3·(H2O) (8) has revealed the nature of the structures; the lanthanide(III) ions are intramolecularly bridged by three phenolic oxygen atoms, forming a dinuclear complex. The lanthanum atom is ten-coordinated, while the erbium atom is nine-coordinated. The coordination polyhedron of the erbium complex is best described as a tricapped trigonal prism.

R = –H or –OH. Solv = EtOH for (1) and Solv = H2O for (6). Two ligand molecules lattice solvent molecules and counter ions are omitted for clarity.Figure optionsDownload as PowerPoint slideHighlights
► Lanthanide complexes of new hydrazones (H3L1 and H5L2) ligands are synthesized.
► Complexes with compositions [Ln2(H2L1)3]3+ and [Ln2(H4L2)3]3+ were isolated.
► La3+ complexes are 10-coordinate; the other lanthanides complexes are 9-coordinate.