Journal of Saudi Chemical Society ( IF 5.6 ) Pub Date : 2019-08-06 , DOI: 10.1016/j.jscs.2019.07.005 Kristin Munkerup , Michael Thulin , Davin Tan , Xiaozhi Lim , Richmond Lee , Kuo-Wei Huang
Advances in processing capabilities of computer clusters have allowed for the full modeling of organometallic complexes that previously would have been simplified to reduce computational cost. Increased feasibility of computational modeling offers new challenges, not only in terms of limitations of methods and theory, but attention should be paid to complexes that can exist in many conformations, as the appropriate choice of conformer may be easily overlooked. In this work a series of pincer complexes with isopropyl and cyclopentyl substituents have been chosen as examples to demonstrate the importance of conformational analysis. The complexes examined contain four isopropyl or cyclopentyl groups on phosphor atoms generating between 27 and 324 possible rotamers. The importance of conformational search in a mechanistic investigation is demonstrated with the CO2 insertion into a nickel hydride bond of POCOP iPr nickel hydride complex. Results show that the reaction energy profile can be both exergonic and endergonic depending on rotamer choice. Specifically, the POCOPiPr Ni-formato complex product of the CO2 insertion reaction had an energy difference between the lowest and highest energy rotamer as high as 16.8 kcal/mol. The significant energy differences between rotamers highlight the importance of thorough conformational analysis and should be taken into consideration when evaluating the energy profile of related reactions.
中文翻译:
彻底的构象分析在过渡金属介导的反应建模中的重要性:含膦基团的钳配合物的案例研究
计算机集群处理能力的进步允许对有机金属配合物进行完整建模,而以前可以简化该模型以降低计算成本。计算模型提供了新的挑战,不仅在方法和理论的局限性方面,但要注意的可行性增加应给予,可以在许多构象存在物,作为构象的适当选择可能很容易被忽视。在这项工作中,选择了一系列具有异丙基和环戊基取代基的钳形配合物作为实例,以证明构象分析的重要性。所检查的配合物在磷原子上包含四个异丙基或环戊基,生成27至324种可能的旋转异构体。2将POCOP i Pr氢化镍配合物插入氢化镍键中。结果表明,取决于旋转异构体的选择,反应能谱既可以是能级的,也可以是能量级的。具体而言,CO 2插入反应的POCOP i Pr Ni-甲酰络合物的最低和最高能量旋转异构体之间的能量差高达16.8 kcal / mol。旋转异构体之间的显着能量差异突出了彻底构象分析的重要性,在评估相关反应的能量分布时应予以考虑。