Syntheses and Structures of Two Series of Coordination Frameworks Based on the Assembly of 1,3,5-Benzenetriacetic Acid with Lanthanide Metal Salts

摘要

Two novel series of coordination frameworks [Ln(bta)(H2O)2]·nH2O·mEtOH(Ln = La 1a,n = 4.5,m = 0;Ln = Ce lb,n = 4,m = 0;Ln = Pr lc,n = 2.88,m = 0,35)and [Ln2(bta)2(H20)3]-"H20(Ln = La 2a,n = 2,14;Ln = Ce 2b,Pr 2c,n = 2)were synthesized by the reaction of 1,3,5-benzenetriacetic acid(Hgbta)with the corresponding lanthanide salts using different methods.X-ray diffraction analyses reveal that all six complexes have 3D channel structures,but in the first series of complexes,each bta3- ligand adopts a cis,trans,trans conformation and acts as a mu5-bridge linking five lanthanide atoms,while in the second series,the bta3- ligands adopt cis,trans,trans and cis,cis,cis conformations and act as mu6- and mu-bridges,respectively.Thus two series of complexes have the same metal atoms and ligands but different structures.The results show that the flexible triacid ligand is versatile and can adopt different conformations according to different reaction conditions,The variable-temperature magnetic susceptibility measurements of complexes lc and 2c showed that both complexes exhibit antiferromagnetic interactions between the Pr(III)ions.