Lanthanide Complexes of Related Click Tripodal 1,2,3-Triazole-Containing Ligands on the Ph3P(O) Platform. The N2 and N3 Coordination of Triazole Fragments

Abstract

The coordination and extraction properties of two related tripodal ligands differed by types of addition of the triazole fragment and linker length in the {2-[(4-Ph-1,2,3-triazol-1-yl)CH₂CH₂O]C₆H₄}₃P(O) (L¹) and {2-[(1-Ph-1,2,3-triazol-4-yl)CH₂O]C₆H₄}₃P(O) (L²) are compared. The structures of the complexes [Lа(NO₃)₃L¹] (I) and [Lu(NO₃)₃L¹] (II) are studied in the solid phase (elemental analysis, IR and Raman spectroscopy) and in solutions (IR and multinuclear ¹H, ¹³C, and ³¹P NMR spectroscopy). A normal coordinate analysis at the TPSS-D4/Def2-SVP level is performed for an isolated molecule of the model complex [La{P(O),N³,N²-L³}(O,O-NO₃)₃] (L³ = {2-[(4-Me-1,2,3-triazol-1-yl)CH₂CH₂O]C₆H₄}₃-P(O)). According to the set of spectral and quantum chemical data, ligand L¹ exhibits the tridentate P(O),N²,N² coordination in lanthanide complexes I and II. These are neutral complexes in the solid state and in CD₃CN solutions, and the dynamic equilibrium of the neutral and ionic complexes is observed in CDCl₃. Unlike ligand L¹, ligand L² exhibits the tetradentate P(O),N³,N³,N³ coordination in the [Ln(NO₃)₃L²] complexes with the same metals (Ln = La³⁺, Lu³⁺) in solutions. The efficiency of extraction of microquantities of f elements from the aqueous phase to 1,2-dichloroethane by compounds L¹ and L² is discussed in comparison with the structures of the complexes of both ligands in solutions.