稀土-对氨基苯甲酸配合物的合成及结构研究

Study on the synthesis and the structures of rare earth complexes with 4-aminobenzoic acid

对氨基苯甲酸与稀土离子在水热条件下反应得到组成为[Ln(p-Ab)3(H2O)]n(p-Ab=对氨基苯甲酸根阴离子,Ln=Sm(1)、Gd(2)、Er(3))的配位聚合物,而Gd(Ⅲ)离子与对氨基苯甲酸在常规溶液条件下反应得到组成为{[Gd(p-Ab)3(H2O)2].H2O}2(4)的双核配合物。配合物(1)-(3)晶体属单斜晶系,P2(1)/n空间群;中心离子配位数为8。配合物为二维层状结构。配合物(4)为双核结构,配体氨基未参与配位。其晶体属三斜晶系,Pī空间群。配位多面体为8配位的双帽三角棱柱体。

Reactions of 4 -aminobenzoic acid with rare earth ions under hydrothermal conditions afforded coordination polymers with the composition of [Ln（p-Ab）3（ H2O）], （p-Ab=anion of 4-aminobenzoic acid, Ln= Sm（I）, Gd（2）, Er（3）） ,while the reaction of Gd（Ⅲ） ion with 4-aminobenzoic acid under normal solution condition provided a discrete dinuclear complex{[ Gd（p-Ab）3（H2O）2]·H20 }2 （4）. The complexes （Ⅰ）, （2）and（3） crystallize in the monoclinic space group P2（I）/n. The eight- coordinated center ions are bridged by 4 - aminobenzoic acid anions, forming a two - dimensional layer structure. The crystal of the dinuclear complex （4）belongs to triclinic system with space group Pi, The Gd atoms adopt a geometry of distorted bicapped trigonal prism constructed by four oxygen atoms from two chelate p- Ab^- ligands, two oxygen atoms of two bridging p-Ab-ligands, and two oxygen atoms of two H20 molecules. The amino N atoms of the ligands are not involved in the coordination.