Stereospecific assembly of chiral Λ-Cr(III)-Δ-Ln(III)-oxalato-bridged dinuclear 3d–4f complexes (Ln = Yb or Dy) and near infrared circular dichroism in the 4f→4f transitions
- 30 January 2001
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 4,p. 492-497
- https://doi.org/10.1039/b007369p
Abstract
Stereospecific formation of the chiral heterodinuclear 3d–4f complexes (Λ–Δ)-[(acac)2Cr(ox)Ln(HBpz3)2] (acac− = acetylacetonate, ox2− = oxalato, HBpz3 − = hydrotris(pyrazol-1-yl)borato; Ln = Yb: 1, Dy: 2 where (Λ–Δ) implies the absolute configuration around the octahedral Cr and square antiprismatic Ln moiety, respectively) was demonstrated by comparing the near infrared circular dichroism (NIR CD) in the 4f→4f transitions and/or the single crystal X-ray analysis with those of a diastereomeric mixture of the mononuclear Λ-, and Δ-[Yb(HBpz3)2(S-pba)] 3 (S-pba = S-(+)-2-phenylbutyrate) complex. The NIR CD spectra for the 4f→4f transitions of the 3d–4f (Λ–Δ)-Cr(ox)Ln complexes 1 and 2 with configurational chirality around the Ln ion with no asymmetric carbon were observed for the first time in CH2Cl2.This observation is supported by the selection rule for the optical activity of the 4f→4f transitions. The first solution NIR magnetic circular dichroism (MCD) of the racemic Cr(ox)Yb and Cr(ox)Dy complexes is also reported.Keywords
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