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

摘要

Reaction of Gd(NO_3)_3·6H_2O with C_6H_5COONa and phen (phen=phenanthroline) produces a binuclear Gd(III) complex of formula [Gd_2(C_(12)H_8N_2)_2(C_6H_5COO)_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(III) ions, two phen molecules and six C_6H_5COO~- groups. The molecular unit is dimeric with an inversion center. Two Gd(II) ions in the molecule are bridged by four C_6H_5COO~- groups and each Gd(III) ion is 8-coordinated in an irregular polyhedron. The Gd-O distances range from 2.322 to 2.509 A, and those of Gd-N from 2.580 to 2.652 A. The Gd-Gd separation is 4.053 A. Magnetic measurements at low temperature reveal a weak antiferromagnetic coupling between two Gd(III) 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.