物理化学学报 >> 2015, Vol. 31 >> Issue (12): 2229-2250.doi: 10.3866/PKU.WHXB201510301

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手性Salen-Ni(Ⅱ)络合物的ECD光谱及其绝对构型关联:可见区第一ECD吸收带的指纹作用

章慧1(),曾丽丽1,王越奎2(),曹石1,郭栋1,李丹1,方雪明1,林丽榕1()   

  1. 1 厦门大学化学化工学院化学系,福建厦门361005
    2 山西大学分子科学研究所,化学生物学与分子工程教育部重点实验室,太原030006
  • 收稿日期:2015-09-09 发布日期:2015-12-04
  • 基金资助:
    国家自然科学基金(21273175, 21273139, 21271150)

Correlation between ECD Spectra and the Absolute Configurations of Chiral Salen-Ni(Ⅱ) Complexes: a Fingerprint Role of the First ECD Band in the Visible Region

Hui. ZHANG1(),Li-Li. ZENG1,Yue-Kui. WANG2(),Shi. CAO1,Dong. GUO1,Dan. LI1,Xue-Ming. FANG1,Li-Rong. LIN1()   

  1. 1 Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
    2 Key Laboratory of Chemical Biology and Molecular Engineering of the Ministry of Education, Institute of Molecular Science, Shanxi University, Taiyuan 030006, P. R. China
  • Received:2015-09-09 Published:2015-12-04
  • Supported by:
    the National Natural Science Foundation of China(21273175, 21273139, 21271150)

摘要:

对系列手性salen-Ni(Ⅱ)络合物的电子圆二色(ECD)光谱及其绝对构型关联进行了概述.根据晶体结构和对固、液ECD光谱的表征,结合理论计算,着重探讨了准平面型手性[Ni(salen)]的固态结构及其在溶液中的绝对构型和优势构象.在此基础上通过若干实例说明了平面四方形[M(salen)]络合物两种绝对构型命名法,并给出了我们的建议.对[Ni(sal-R, R-chxn)] [sal-R, R-chxn = (R, R)-N, N'-双(亚水杨基)-1, 2-二亚氨基环己烷]的二氯甲烷溶液ECD光谱的计算结果表明,可见区第一个ECD吸收带主要是πd荷移跃迁(LMCT)所致,而不是通常认为的d-d跃迁: [Ni(sal-R, R-chxn)]的绝对构型为Λ,其在可见区第一个ECD吸收带为正.将此ECD指纹应用于具有“闭壳层”电子结构的其它平面型手性[Ni(salen)]和六配位trans-[Co(salen)L2]络合物的绝对构型指认,具有一定的普适性.本文的研究结果对于深入理解手性[M(salen)]络合物的配位立体化学、手征光学性质及其手性识别和不对称催化机理具有重要科学意义.

关键词: Salen-Ni(Ⅱ)络合物, 电子圆二色, 固体手性光谱, 绝对构型关联, 指纹技术

Abstract:

A correlation between the electronic circular dichroism (ECD) spectra and the absolute configurations of a serials' chiral salen-Ni(Ⅱ) complexes was investigated. The solid-state structures, absolute configurations, and preferential conformations in solution of quasi-planar chiral [Ni(salen)] complexes were studied using their crystal structures, solid-state and solution ECD spectra in combination with theoretical ECD calculations. Furthermore, two different nomenclatures for the absolute configurations of square-planar [M(salen)] complexes were inspected carefully, and suggestions for proper use of them are discussed. The calculated ECD spectra of [Ni(sal-R, R-chxn)] [sal-R, R-chxn = (R, R)-1, 2-cyclohexylene bis(salicylicdeneiminate)] in dichloromethane solution revealed that the first ECD band in the visible region was dominated by the ligandto-metal charge transfer transition (LMCT), which was incorrectly assigned to a d-d transition in the literature. When the absolute configuration of [Ni(sal-R, R-chxn)] was Λ, the first ECD absorption band in the visible region was positive. This ECD fingerprint is universally applicable for assigning the absolute configurations of other square-planar chiral [Ni(salen)] and six-coordinate trans-[Co(salen)L2] complexes with a "closed-shell" electronic structure. This work provides some insight into the coordination stereochemistry and chiroptical properties of chiral [M(salen)] complexes. Additionally, this work is significant for the understanding of chiral recognition and asymmetric catalytic mechanisms.

Key words: Salen-based Ni(Ⅱ) complex, Electronic circular dichroism, Solid-state chiroptical spectroscopy, Absolute configuration correlation, Fingerprint technique

MSC2000: 

  • O641