Dinuclear and two- and three-dimensional gadolinium(III) complexes with mono- and dicarboxylate ligands: synthesis, structure and magnetic properties

作者：Canadillas Delgado Laura; Fabelo Oscar; Cano Joan; Pasan Jorge; Delgado Fernando S; Lloret Francesc; Julve Miguel; Ruiz Perez Catalina^*

来源：CrystEngComm, 2009, 11(10): 2131-2142.

DOI：10.1039/b904764f

Three new gadolinium(III) complexes with carboxylate ligands of formula [Gd-2(ac)(6)(H2O)(4)]center dot 2H(2)O (1), [Gd-2(ac)(2)(fum)(2)(H2O)(4)](n) (2) and [Gd-2(ox)(fum)(2)(H2O)(4)](n)center dot 4nH(2)O (3) (ac = acetate, fum = fumarate and ox oxalate) have been prepared and their structures determined by X-ray diffraction on single crystals. The structure of 1 is made up of discrete centrosymmetric di-mu-oxo( carboxylate acetate) digadolinium( III) units with an intramolecular Gd center dot center dot center dot Gd separation of 4.1589(3) angstrom. Each gadolinium atom in 1 is nine-coordinated with two water molecules and seven carboxylate-oxygen atoms from four acetate ligands building a monocapped square antiprism environment. Compound 2 exhibits a sheet-like structure, the repeating intralayer motif being a rectangle of di-m-oxo( carboxylate acetate) digadolinium(III) units [Gd center dot center dot center dot Gd separation of 3.8659(10) angstrom] where the edges are defined by bridging bis-bidentate and tetrakis-monodentate fumarate groups. Each gadolinium atom in 2 is nine-coordinated with two water molecules and seven carboxylate oxygens from two acetate and three fumarate ligands building a distorted monocapped square antiprism. Compound 3 has a three-dimensional structure where chains of double oxo(carboxylate fumarate)-bridged gadolinium( III) ions are interlinked by bis-bidentate fumarate to afford layers which are further interconnected through bis-bidentate oxalate ligands. The corresponding values of the Gd center dot center dot center dot Gd separation are 4.5816(1), 8.2292(2) and 6.2989(1) A. Each gadolinium atom in 3 is ten-coordinated with two water molecules and eight oxygen atoms from four fumarate ligands and one oxalate group building a distorted bicapped square antiprism. Variable-temperature magnetic susceptibility measurements show the occurrence of weak but significant ferro- (1 and 3) and antiferromagnetic (2) interactions through the double oxo(carboxylate acetate) (1 and 2), double syn-syn carboxylate fumarate (2) and double oxo( carboxylate fumarate) and bis-bidentate oxalate (3) bridges. Monte Carlo calculations were performed in the case of 3 to simulate its magnetic data and to substantiate the best-fit values of the magnetic couplings through the different exchange pathways involved.

• 出版日期2009