Synthesis and structural determination of mononuclear eight-coordinate (EnH)[Lu-III(Egta)] center dot 2H(2)O and 2D ladder-like nine-coordinate (EnH2)[Y-III(Egta)(H2O)](2) center dot 6H(2)O

摘要

Two novel lanthanide complexes, (EnH)[Lu-III(Egta)] center dot 2H(2)O (I) and (EnH(2))[Y-III(Egta)H2O](2) center dot 6H(2)O (II), where En = ethylenediamine and H(4)Egta = ethyleneglycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid, have been successfully synthesized through direct heating reflux and their molecular crystal structures were determined by FT-IR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques (CIF files CCDC nos. 966211 (I) and 966210 (II)). X-ray diffraction reveals that I has a eight-coordinate mononuclear structure with distorted square antiprismatic conformation. The reason that the Lu(III) adopts a eight-coordinate conformation is the small ionic radius and more f-orbital electrons, which generates a relatively small coordination number. Complex I crystallizes in a orthorhombic system with Pca2(1) space group. The crystal data are as follows: a = 22.4933(14), b = 9.1067(7), c = 10.6450(5) and V = 2180.5(2) (3). Complex II takes nine-coordinated structure with a monocapped square antiprism, and crystallizing in the monoclinic crystal system with P2(1)/c space group. The cell dimensions are as follows: a = 12.9600(11), b = 12.6209(12), c = 16.9151(15) , beta = 122.021(2)A degrees and V = 2345.8(4) (3). Each ethylenediammonium (EnH (2) (2+) ) cation in (EnH(2))[Y-III(Egta)H2O](2) center dot 6H(2)O (II) connects three adjacent [Y-III(Egta)(H2O)] (2) (2-) anions through hydrogen bonds. While in II, there are two types of EnH (2) (2+) cations, which form hydrogen bonds with the neighboring [Y-III(Egta)(H2O)] (2) (2-) anions, leading to the formation of a 2D ladder-like layer structure. The results showed that the ionic radius of rare earth metals play a crucial role in crystal and molecular structure of their complexes.