摘要:
IntroductionThe design of new solid-state architectures has recently driven muchattention and increasing interest.1Advancedcrystal engineering by selecting structural ligands and the coordination geometryof lanthanide(III) metal centers as a building blockcan give a series of novel inorganic frameworks with an interesting varietyof crystal-packing motifs. This is in accordance with the experience thatthe crystal structures of the lanthanide compounds frequently change alongthe series as a result of the lanthanide contraction.Among a number of ligands used as building blocks, the two end functionalgroups of dicarboxylic acids could yield a variety of crystal structures ofcoordination compounds even with close chemical formulae, depending on theconformation of the carbon chains and the end functional groups. Those compoundsare characterized as organic/inorganic hybrids with pillared sheet-likestructures assembled from the molecular precursor in solution.In order to check the ability of rare earth ions to lead to high dimensionalmaterials, we have thus undertaken a study of the lanthanide malonate complexes (wheremalonate stands for the dianion of the propanedioic acid, H2mal).This ligand has, indeed, a great ability to form infinite connections withmetal ions2,3and a remarkable versatilityin adopting several different modes of bonding, ranging from unidentate, chelatingand bridging, sometimes in more than one way in the same compound. Seven bondingmodes have been observed according to the coordination environment of COO−groups as shown inScheme 1.Also, malonic acid is widely used in many important fields as a resultof its excellent coordination ability. The complexes of malonic acid withlanthanide and transition elements have been used in the fluorescent probetechnique, solid fluorescent materials, biological active materials and modifiersof polyethylene.4,5Therefore, studiesof the new complexes with malonic acid are quite valuable in theory and application.In this paper we describe the synthesis, IR spectrum, thermal behaviour,magnetic properties and crystal structure of [Pr2(mal)3(H2O)3]·2H2O, (1).
ISSN:1466-8033
DOI:10.1039/b006256l
出版商:RSC
年代:2000
数据来源: RSC