5 - Methyl Isophthalic Acid Lanthanide Metal Complexes Preparation, Structure, And Standard Molar Enthalpy Of Formation

Constructing ordered structure polymer is one of the hot topics of coordination chemistry and material science in last decade. The key factor that affects the structure and property of coordination polymers is the characteristic ligand. The property of ligand is not only decided by the coordinated groups, but also is attributed by uncoordinated groups. We build this thesis on the previous work of the complexes based on 5-nitroisophthalic acid and lanthanide metals. Instead of 5-nitroisophthalic acid,5-methylisophthalic acid is selected for building compound with lanthanide metals. Furthermore, the thermodynamic properties of these series of complexes are investigated and the conclusions are following:1. The complexes 1-4 are prepared by reaction of 5-nitroisophthalic acid and lanthanide metals in solution. The single crystal structure reveals that the complexes could be divided into 3 groups accompanied by the atomic number changing. Comparing those of complexes based on 5-nitroisophthalic acid lanthanide, the structures of corresponding lanthanide complexes change with the uncoordinated groups effect.2. The measurements of TG-DTG are used to analyze the thermodynamic stabilities of complexes. The same processes of dehydration in complexes 14 are observed and the complexes further decompose corresponding lanthanide oxide. The procedures of the title complexes can not be divided into 3 groups, because lanthanide complexes contain more water molecules and the processes of dehydration are more complicated.3. The standard molar enthalpies of formation of the complexes are determined by an RD-496 typed calorimeter. The plots of the experimental Standard molar enthalpies against the lanthanide atom numbers exhibit "triple groups", which is consistent with that of the crystal structure of the series complexes. This "triple groups" effect is differrent with that of the complexes based on 5-nitroisophthalic acid. The different is caused by uncoordinated group.