二茂基镧系8-羟基喹啉化合物的合成及其热稳定性研究

Synthesis and Studies on Thermal Stability of Dicyclopentadienyl Lanthanide 8-hydroxyquinolinolato Complexes

通过三茂基镧系化合物Cp_3Ln(Cp=C_5H_5;Ln=Sm,Dy,Ho)与8-羟基喹啉反应(HL),合成了3种新的镧系金属有机化合物,通式为Cp_2LnL(Ln=Sm,Dy,Ho)。经元素分析、红外光谱、X光电子能谱、质谱及分子量测定,推断化合物具有二聚体结构,分子内存在通过喹啉氮原子和氧原子与金属配位而形成的五元螯合环。对化合物的热稳定性进行了研究和比较,发现化合物Cp_2SmL对热不稳定,在180℃以上分解为Cp_3Sm和SmL_3。

By using the reaction of Cp3Ln(Cp = C5H5; Ln = Sm, Dy, Ho) with 8-hydroxyquinoline (HL)(1:1 molar ratio) in tetrahydrofuran at room temperature, three new organoianthanide complexes with the general formula Cp2LnL( Ln = Sm, Dy , Ho) were synthesized. All the complexes were characterized by elementary analysis, 1R, XPS, MS spectra and cryoscopic method for molecular weight determination. The results of elemental analyses confirmed to the formula Cp2LnL. The IR spectra show the characteristic absorptions of η5-Cp group at about 3100, 1440, 1010, 780 and 250 cm-1, and 8-hydroxyquinolino!ato metal chelates near 560 cm-1. XPS data revealed that the N,, binding energy of L ligand in each complex is higher than that of sodium salt of 8-hydroxyquinoline, which indicates that L iigand coordinates to metal through nitrogen and oxygen atoms to form an intramolecular five-membered chelating ring. Molecular weight determination by cryoscopic method in benzene suggests each complex exists as a dimer with oxygen atoms of L ligands as bridging atoms. MS spectra show only the monorneric molecular ion peaks of the complexes, which may indicate that upon heating, the dimeric complexes easily dissociate into a monomer. Due to the effect of chelating coordination, the title complexes have higher stability compared to the corresponding Cp2LnCl and Cp3Ln complexes. The thermal stabilities of the complexes were studied and compared eath other. Complex Cp2SmL is thermally unstable and tends to decompose into Cp3Sm and SmL3 at above 180℃.