The photophysical properties of lanthanide(III) complexes depend on the magnitude of orbital mixing between the lanthanide(III) and ligands. Herein, an estimation method of orbital mixing in lanthanide(III) complexes is reported using LnCl₃⋅nH₂O (Ln=Pr, Gd, Tb) and Ln(tfa)₃(H₂O)₂ (tfa: trifluoroacetylacetonate, Ln=Pr, Gd, and Tb) for the first time. The electronic state properties were assessed from the electronic absorption and magnetic circular dichroism (MCD) spectra. The MCD spectra revealed the energy levels of the spin‐allowed and spin‐forbidden 4 f–5d transitions of the Tb(III) complex that is hidden by the intense π–π* transition of the ligands. This energy gap corresponds to the exchange splitting energy between the 5d and 4fⁿ⁻¹ electrons, which provides information regarding the orbital mixing between the Tb(III) ion and the ligands.

中文翻译：

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磁性圆二色性估算镧系元素（Ⅲ）配合物中金属配体轨道混合的方法

镧系元素（III）配合物的光物理性质取决于镧系元素（III）与配体之间的轨道混合程度。这里，镧系元素中的（III）配合物混合轨道的估计方法是使用LnCl报道₃ ⋅ Ñ ħ ₂ O（LN = PR，钆，铽）和LN（TFA）₃（H ₂ O）₂（tfa：三氟乙酰丙酮，Ln = Pr，Gd和Tb）第一次。从电子吸收光谱和磁圆二向色性（MCD）光谱评估了电子态性质。MCD光谱揭示了Tb（III）配合物的自旋允许和自旋禁止的4 f-5d跃迁的能级，该跃迁被配体的强烈π-π*跃迁所掩盖。该能隙对应于5d和4f ^n-1电子之间的交换分裂能，它提供了有关Tb（III）离子与配体之间的轨道混合的信息。