Halogen Bonding Involving I2 and d8 Transition-Metal Pincer Complexes
Halogen Bonding Involving I2 and d8 Transition-Metal Pincer Complexes
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DOI：
10.3390/cryst11040373
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发表时间：
2021-04-01
期刊：
影响因子：
2.7
通讯作者：
Kraka, Elfi
中科院分区：
文献类型：
--
作者：
Freindorf, Marek;Yannacone, Seth;Kraka, Elfi
采用PBE 0-D3（BJ）/aug-cc-pVTZ/PP（M，I）模型化学，系统研究了货车Koten钳形配合物中碘-金属和碘-碘键合以及19种取代基和/或过渡金属的修饰.作为一种新的工具，在这些配合物中的碘-金属和碘-碘键强度的定量评估，我们使用的本地模式分析，最初介绍的Konkoli和Cremer，补充NBO和巴德的QTAIM分析。我们的研究揭示了钳形配合物的M-I-I非经典三中心键的催化活性中的主要电子效应，该键参与了分子碘I-2对金属中心的氧化加成。根据我们的研究，从金属到I-I键的σ * 反键轨道的电荷转移改变了M-I-I三中心键的3c-4 e特征，这导致碘I-I键的减弱和金属-碘M-I键的加强，从而以这种方式促进I-2对金属的氧化加成。通过在钳形络合物的不同位置和通过不同的过渡金属进行取代，可以系统地改变电荷转移，从而改变M-I和I-2键的强度。我们还模拟了不同极性的溶剂如何影响M-I-I键的3c-4 e特征。我们的研究结果提供了新的指导方针的钳配合物的设计与特定的碘-金属键强度，并介绍了本地振动模式分析作为一种有效的工具，以评估在配合物中的键强度。
We systematically investigated iodine-metal and iodine-iodine bonding in van Koten's pincer complex and 19 modifications changing substituents and/or the transition metal with a PBE0-D3(BJ)/aug-cc-pVTZ/PP(M,I) model chemistry. As a novel tool for the quantitative assessment of the iodine-metal and iodine-iodine bond strength in these complexes we used the local mode analysis, originally introduced by Konkoli and Cremer, complemented with NBO and Bader's QTAIM analyses. Our study reveals the major electronic effects in the catalytic activity of the M-I-I non-classical three-center bond of the pincer complex, which is involved in the oxidative addition of molecular iodine I-2 to the metal center. According to our investigations the charge transfer from the metal to the sigma* antibonding orbital of the I-I bond changes the 3c-4e character of the M-I-I three-center bond, which leads to weakening of the iodine I-I bond and strengthening of the metal-iodine M-I bond, facilitating in this way the oxidative addition of I-2 to the metal. The charge transfer can be systematically modified by substitution at different places of the pincer complex and by different transition metals, changing the strength of both the M-I and the I-2 bonds. We also modeled for the original pincer complex how solvents with different polarity influence the 3c-4e character of the M-I-I bond. Our results provide new guidelines for the design of pincer complexes with specific iodine-metal bond strengths and introduce the local vibrational mode analysis as an efficient tool to assess the bond strength in complexes.