Syntheses and Vibrational Circular Dichroism Spectra of the Complete Series of [Ru((−)- or (+)-tfac)_<i>n</i>(acac)_3−<i>n</i>] (<i>n</i> = 0 ∼ 3, tfac = 3-Trifluoroacetylcamphorato and acac = Acetylacetonato)

Twenty four kinds of Ru(III) complexes expressed by the formula of Δ- or Λ-[Ru((−)- or (+)-tfac)n(acac)3−n] (n = 1, 2, and 3, (−)- or (+)-tfac = (−)- or (+)-3-trifluoroacetylcamphorato and acac = acetylacetonato) were prepared in a pure diastereomeric form. The separation of these diastereomers was accomplished chromatographically by rational use of two antipodal chiral columns. The separated complexes were identified by means of mass spectra, 1H NMR, electronic circular dichroism, and partly X-ray diffraction analyses. When a pair of Δ- and Λ-[Ru(acac)3] (n = 0) was added to this group, they constituted the complete series of mixed ligand complexes including ligand chirality under the condition of no mixing of chiral ligands. The vibrational circular dichroism (VCD) spectra of their CDCl3 solutions were recorded in the wavenumber region of 1000∼1800 cm−1. The results provided a benchmark for systematically examining the effects of the stereochemical properties on VCD spectra such as the degree of ligand substitution, ΔΛ configurations, geometrical isomerism, and ligand chirality. As a result, the geometrical isomers of trans- or cis-[Ru((−)- or (+)-tfac)2(acac)] and mer- or fac-[Ru((−)- or (+)-tfac)3] were clearly differentiated by their VCD signals, which was hardly possible from their IR spectra alone.本研究制备了24种通式为Δ-或Λ-[Ru((−)-或(+)-tfac)ₙ(acac)₃₋ₙ]的钌(III)配合物（n=1、2、3；(−)-或(+)-tfac=(−)-或(+)-3-三氟乙酰樟脑合基（3-trifluoroacetylcamphorato），acac=乙酰丙酮合基（acetylacetonato）），所有产物均为单一非对映异构体纯品。通过合理联用两支对映手性色谱柱，采用色谱法完成了该系列非对映异构体的分离。采用质谱、¹H核磁共振波谱、电子圆二色光谱及部分X射线衍射分析对分离得到的配合物进行了结构鉴定。向该系列中加入一对Δ-和Λ-[Ru(acac)₃]（n=0）后，即可得到在不混配手性配体的条件下涵盖配体手性因素的完整混合配体配合物系列。在1000~1800 cm⁻¹的波数范围内，记录了其氘代氯仿（CDCl₃）溶液的振动圆二色光谱（Vibrational Circular Dichroism, VCD）。该研究结果为系统考察立体化学性质对振动圆二色光谱的影响提供了基准参照，这些立体化学性质包括配体取代度、ΔΛ构型、几何异构及配体手性。结果表明，反式（trans-）或顺式（cis-）-[Ru((−)-或(+)-tfac)₂(acac)]以及经式（mer-）或面式（fac-）-[Ru((−)-或(+)-tfac)₃]的几何异构体可通过其VCD信号实现清晰区分，而仅依靠红外光谱则难以完成该区分。