A tripod ligand, 1,1,1 tri [1′ (2′ oxa 5′ oxo 6′ aza 6′ bisphenyl)hexyl] propane(L), and its complexes with Ln(NO 3) 3 · n H 2O(where Ln=La, Ce, Pr, Nd) have been synthesized. These new complexes with the general formula of Ln 2L(NO 3) 6· n H 2O(where Ln=La, n =4; Ln=Pr, n =2; Ln=Ce, Nd, n =1) were characterized by elemental analysis, IR spectra, thermal analysis, 1H NMR spectra and molar conductivity. All the complexes are stable in air and their conductances in acetonitrile solution lie in the 149—158 S·cm 2·mol -1 range, indicating that they are 1∶1 type electrolytes. The IR and 1H NMR spectra of the ligand and its complexes show that all the ether oxygen atoms and the CO groups take part in coordination to the metal ions, and the larger shift for ν CO in the IR spectra of the complexes suggests that the Ln—O(carbonyl) bond is stronger than the Ln—O(ether) one which also was inferred from the 1H NMR spectral data . The thermal behaviour of the complexes are similar. The first loss occurs at 85—100.9 ℃ corresponding to the loss of all the water molecules. The weight losses found in this process compare favourably with the theoretical values. Moreover, the relatively low temperatures of dehydration are consistent with the presence of crystal water.
