Abstract
The reactions of Ln(NO3)3∙6H2O (Ln=Pr, Nd or Er) with the potentially tridentate O,N,O chelating ligand 2,6-pyridinedimethanol (H2pydm) in a 1:2 M ratio were investigated, and complexes with the formula [Ln(H2pydm)2(NO3)2](NO3) (Ln=Pr or Nd) (1 and 2) and [Er(H2pydm)3](NO3)3 (3) were isolated. The compounds contain 10-coordinate Pr(III) and Nd(III) ions that crystallize in the triclinic space group P-1 while the 9-coordinate Er(III) complex crystallizes in the monoclinic system (P21/n). A new lanthanide complex, [Pr(H2pydm)3](Cl)3∙DMF (4), has been synthesized by reaction of PrCl3∙6H2O and H2pydm. The nine-coordinate Pr(III) is bound to three H2pydm ligands. X-ray crystal structures of 1–4 reveal that the ligand coordinates tridentate via the pyridyl nitrogen and the two hydroxyl oxygens. The electronic absorption spectra of 1–4 show 4f–4f transitions.
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