Studies On Syntheses And Structures Of Several Rare Earth Metal Ions-H₆ttha, H₅dtpa And H₄egta Complexes

Three kinds of aminopolycarboxylic acid: H₆ttha, H5dtpa and H₄egta werechosen as ligands, and they were synthesized with rare earth metals to form sixcomplexes as followed:（mnH）₂[Dy^Ⅲ（Httha）]·3H₂O,（enH₂）3[Dy^Ⅲ（ttha）]₂·9H₂O,（mnH）₄[Sm^Ⅲ（dtpa）]₂·6H₂O,（mnH）₄[Ho^Ⅲ₂（dtpa）₂]·12H₂O,（mnH）₄[Y^Ⅲ₂（dtpa）₂]·12H₂O and （enH₂）[Yb^Ⅲ（egta）（H₂O）]₂·6H₂O. According to thekind of the ligands, the molecular structure, crystal structure and coordinationstructure of these complexes are studied detailed and carefully. And it goes a stepfurther to validate that the structures of rare earth metal complexes withaminopolycarboxylic acid are related closely to the ionic radius, electronicconfiguration and oxidation state of central metal ions as well as the shape ofaminopolycarboxylic acid ligands and the counter ion species.The thesis is divided into three parts on the basis of the kind of the ligands.In the first part we chose decadentate H₆ttha as ligand, DyⅢ as metal ions,methylamine and ethylenediamine as counter ion by using direct heating refluxmethod successfully synthesized two novel complexes, namely,（mnH）₂[Dy^Ⅲ（Httha）]·3H₂O （mn=methylamine） and （enH₂）3[Dy^Ⅲ（ttha）]₂·9H₂O （en=ethylenediamine）. Although these coordinate number of these two complexes is nineand adopts pseudo-monocapped square antiprism conformation. Different counter ionresult in different molecular and crystal structure of these two complexes.（mnH）₂[Dy^Ⅲ（Httha）]·3H₂O is monoclinic crystal system with P2（1）/c space group. Inaddition, it can also be seen that this nine-coordinate complex contains anon-coordinate carboxyl group （–CH2COOH）. This place is very special because itmay be modified by some functional groups or biological molecules to become aspecific target drug with great diagnostic and therapeutic effect.（enH₂）3[Dy^Ⅲ（ttha）]₂·9H₂O crystallizes in the monoclinic crystal system, P2/c spacegroup.（enH₂）3[Dy^Ⅲ（ttha）]₂·9H₂O contain two types of enH₂2+. The two neighboring[Dy^Ⅲ（ttha）]3–complex anions are further connected by sharing two ethylenediamines （N（5）-C（19）-C（20）-N（6）） along a-aixs, resulting in the formation of infinite1-D chain.The two1D chains are linked by sharing the ethylenediamine（N（5）-C（19）-C（20）-N（6）） in the ac plane, leading to the formation of close-knit2-Dladder-like network.In the second part we chose the octadentate H5dtpa as ligand, Sm^Ⅲ, HoⅢ,YⅢ as metal ions, methylamine as counter ion by using direct heating refluxmethod successfully synthesized three novel complexes, namely,（mnH）₄[Sm^Ⅲ（dtpa）]₂·6H₂O,（mnH）₄[Ho^Ⅲ₂（dtpa）₂]·12H₂O and（mnH）₄[Y^Ⅲ₂（dtpa）₂]·12H₂O. And then, they were characterized by means ofelemental analysis, FT-IR spectrum, thermal analysis and single-crystal X-raydiffraction. Three rare earth amino acid complexes adopt nine-coordinate binuclearstructure with tricapped trigonal prismatic conformation. In the virtue of differentcentral metal ions, these two complexes have different structures. By contrast, if theearth metals are similar in the ion radii, crystal structure crystal system and spacegroup are also similar. If the earth metals are very different in the ion radii, crystalstructure crystal system and space group are also significantly different.In the third part we chose octadentate H₄egta as ligand, YbⅢ as metal ions,ethylenediamine as counter ion by using direct heating reflux method successfullysynthesized one novel complexes, namely,（enH₂）[Yb^Ⅲ（egta）（H₂O）]₂·6H₂O. Itcrystallizes in the monoclinic crystal system, P21/n space group. H₄egta create sevenfive-membered chelating rings with the central YbⅢ ion in which the five atoms arealmost coplanar in each ring. Each ethylenediamine cation （enH₂2+） connects threeadjacent [Yb^Ⅲ（egta）（H₂O）]–through hydrogen bonds, leading to the formation of a2-D ladder-like layer structure.