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 Delta-M[Ln((+)-hfbc)(4)] (M(I) = Na, K, Rb, Cs; Ln(III) = La, Eu; abbreviated as M-Ln) and Delta-Cs[Yb((+)-hfbc)(4)] (Cs-Yb) were observed in CDCl(3) solutions. The VCD signs and/or intensities are mostly different from those of the Delta-tris(beta-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 Delta-M-La complexes is observed similarly for the Delta-tris(beta-diketonato) complexes, confirming the assignment to the Delta 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 Delta-M-La(III) complexes.