| 一类混配型钌苯配合物的手征光学特性 | |
| Chiroptical Properties of Mixed-Ligand Ruthenabenzene Complex | |
| 摘要: 手性钌配合物反应机理及手性构性关系的理论研究是一个重要课题。本工作中，用密度泛函方法研究了一类混配型钌苯配合物[RuBen (PPh3)2(Phen)(L-Cys)]2+(Phen=菲咯啉，L-Cys=L-半胱氨酸)的几何构型、电子结构和手征光学性质。计算拟合的电子圆二色(ECD)谱的峰形、符号与相对强度均与实验谱图吻合。各手征结构单元中，八面体内核的Λ/Δ-构型主导ECD曲线的分布，螯合环L-Cys的λ/δ折叠只影响吸收带的相对强度，而R/S手性碳的贡献极小。340nm以上的吸收带由π→π*跃迁主导，混有部分Ru中心的d→d成分。340nm以下有一强一弱2对谱带，分属于典型和非典型的激子耦合。二者对Λ-构型均表现为正的手性激子裂分。该特征可作为指认类似配合物绝对构型的参考判据。此外，通过与混配型无机钌配合物比较，讨论了二者手征光学特性的异同。 | |
| 关键词: 钌苯配合物 电子圆二色谱 手征光学性质 激子手性方法 激子耦合 | |
| 基金项目: 国家自然科学基金(No.21776199)、山西省高等学校科技创新项目(No.2019L0805)和山西省应用基础研究计划项目(No.201801D221080)资助。 | |
| Abstract: The theoretical study of reaction mechanism and relationship between chiral configuration and property of chiral ruthenium complexes is an important topic. In this work, the chiroptical properties of the mixed-ligand ruthenabenzene complex [RuBen(PPh3)2(Phen) (L - Cys)]2+ (Phen=phenanthroline, L - Cys=L - cysteine) have been explored using the hybrid density functional theory (DFT). The geometrical and electronic structures and subsequent frequency verifications were calculated using the B3LYP method with the mixed basis set: the ECP28MWB pseudopotential with its (8s7p6d2f )/[6s5p3d2f ] valence basis set for ruthenium, and 6 - 311G(d) for other atoms. Based on these, the excited energies, rotational and oscillator strengths, as well as the electronic circular dichroism (ECD) spectra, were then calculated employing the time-dependent DFT method with the same functional and basis set. In all cases, solvent (water) effects were included using the polarized continuum model (PCM). Additionally, the intricate exciton- splitting pattern in the short wavelength region was analyzed using the exciton chirality method (ECM). The calculated ECD spectra were in good agreement with the observed ones as far as their band shape, signs, and relative intensities were concerned. The Λ/Δ configurations at the octahedral core dominate the distribution of the ECD curves, and the λ/δ twists of the L-Cys rings only affect the relative intensities of the absorption bands, while the contributions of the R/S chiral carbon atoms are negligible. The absorption bands above 340 nm are characterized by the π→π* transitions mixed with some metal- centered d→d transitions. The two pairs of ECD bands below 340 nm with clearly different intensities could be assigned to the classical (the strong one) and nonclassical (the weak one) exciton coupling, respectively. Both show a positive exciton - splitting pattern for the Λ-configuration, which could be used as a criterion to determine the absolute configurations of similar complexes. Additionally, comparing with mixed-ligand inorganic ruthenium complexes reveals the similarities and differences in their chiroptical properties. | |
| Keywords: ruthenabenzene complex electronic circular dichroism spectrum chiroptical properties exciton chirality method exciton coupling | |
| 投稿时间：2021-11-07 修订日期：2022-02-18 | |
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| 冯丽霞,刘巧玲,冯思思,侯玉翠,王越奎.一类混配型钌苯配合物的手征光学特性[J].无机化学学报,2022,38(4):665-674. | |
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