Vibrational Circular Dichroism of Δ-SAPR-8-tetrakis[(+)-heptafluorobutyrylcamphorato]lanthanide(III) Complexes with an Encapsulated Alkali Metal Ion

The vibrational circular dichroism (VCD) spectra for Δ-M[Ln((+)-hfbc) 4 ] (M I = Na, K, Rb, Cs; Ln III = La, Eu; abbreviated as M-Ln) and Δ-Cs[Yb((+)-hfbc) 4 ] (Cs-Yb) were observed in CDCI 3 solutions. The VCD signs and/or intensities are mostly different from those of the Δ-tris(β-diketonato) transition-metal complexes. The M-Ln complexes give the strong VCD peak(s) near 1550 cm -1 . These VCD patterns are different from each lanthanide(III) complex, but their intensities change with variation of the alkali metal ion. A positive-negative couplet VCD near 1550 cm -1 for the Δ-M-La complexes is observed similarly for the Δ-trips-(β-diketonato) complexes, confirming the assignment to the Δ absolute configuration based on the exciton CD. The density functional theory calculated VCD for the two peaks at 1650 and 1550 cm -1 reproduces the relative intensity and signs of the observed ones for the Δ-M-La III complexes.