Synthesis, structure and characterization of Gd(III) dimer bridged by tetra benzoates

Reaction of Gd(NO3)(3)(.)6H(2)O with C6H5COONa and phen (phen=phenanthroline) produces a binuclear Gd(III) complex of formula [Gd-2(C12H8N2)(2)(C6H5COO)(6)]. Structure and magnetism of the product have been studied by X-ray diffraction and magnetic susceptibility measurement. The molecule of the complex contains two Gd(Ill) ions, two phen molecules and six C6H5COO- groups. The molecular unit is dimeric with an inversion center. Two Gd(III) ions in the molecule are bridged by four C6H5COO- groups and each Gd(Ill) ion is 8-coordinated in an irregular polyhedron. The Gd-O distances range from 2.322 to 2.509 Angstrom, and those of Gd-N from 2.580 to 2.652 Angstrom. The Gd-Gd separation is 4.053 A. Magnetic measurements at low temperature reveal a weak antiferromagnetic coupling between two Gd(Ill) ions in the dimer (J = -0.43 cm(-1) g = 1.94). The IR and UV-VIS-NIR spectra of the dimer have been measured and analyzed. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.Chemistry, Inorganic & NuclearChemistry, PhysicalPhysics, Condensed MatterSCI(E)32ARTICLE81103-1106