Full Conformational Analyses of the Ultrafast Isomerization in Penta-coordinated Ru(S 2 C 2 (CF 3 ) 2 )(CO)(PPh 3 ) 2 : One Compound, Two Crystal Structures, Three CO Frequencies, 24 Stereoisomers, and 48 Transition States
Full Conformational Analyses of the Ultrafast Isomerization in Penta-coordinated Ru(S 2 C 2 (CF 3 ) 2 )(CO)(PPh 3 ) 2 : One Compound, Two Crystal Structures, Three CO Frequencies, 24 Stereoisomers, and 48 Transition States
复制标题
五配位 Ru(S 2 C 2 (CF 3 ) 2 )(CO)(PPh 3 ) 2 超快异构化的完整构象分析：一种化合物、两种晶体结构、三种 CO 频率、24 种立体异构体和 48 种过渡态
DOI：
10.1021/acs.inorgchem.0c01708
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发表时间：
2020
影响因子：
4.6
通讯作者：
Hall, Michael B.
中科院分区：
文献类型：
--
作者：
Tang, Hao;Porter, Tyler M.;Kubiak, Clifford P.;Hall, Michael B.
用密度泛函理论（DFT）研究了五配位钌配合物Ru（S2 C2（CF 3）2）（CO）（PPh 3）2的超快（皮秒）异构化反应的立体动力学.钌络合物以两种几乎正方形金字塔（SP）形式结晶。紫色形式具有顶端PPh 3配体，橙子形式具有顶端CO配体，并且它们的溶液显示三个CO伸缩频率。有4个可能的手性中心（1个钌，2个膦和1个二硫醇盐），有24个立体异构体。这些立体异构体的DFT计算表明，结构范围从几乎完美的SP（τ5 <$0）的结构显着扭曲向三角双锥（TBP）（τ5 <$0.6）。立体异构体可分为三组，νCO分别为1960 cm-1、1940 cm-1和1980 cm-1。这些异构体被发现通过Ru-S键扭转，CF 3旋转，苯基扭转，PPh 3旋转，并在某些情况下，通过耦合运动在相对较小的障碍相互转化。复合能面分析表明，低能结构间的相互转化可以通过直接和间接两种途径进行，但通过νCO ~（1980 cm-1）族同分异构体的间接途径更为有利，这与最近的实验结果一致.这项工作提供了第一个完整的五配位，扭曲的SP，d 6-过渡金属配合物的超快异构化的机理图片。
The stereodynamics of an ultrafast (picosecond) isomerization in a penta-coordinated ruthenium complex, Ru(S2C2(CF3)2)(CO)(PPh3)2, were characterized by density functional theory (DFT). The ruthenium complex crystallizes in two almost-square pyramidal (SP) forms. The violet form has an apical PPh3ligand, the orange form has an apical CO ligand, and their solution displays three CO stretching frequencies. With 4 possible centers of chirality (1 ruthenium, 2 phosphines, and 1 dithiolate), there are 24 stereoisomers. DFT calculations of these stereoisomers show structures ranging from almost-perfect SP (τ5≈ 0) to structures significantly distorted toward trigonal bipyramidal (TBP) (τ5≈ 0.6). The stereoisomers fall neatly into three groups, with νCO≈ 1960 cm–1, 1940 cm–1, and 1980 cm–1. These isomers were found to interconvert over relatively small barriers via Ru–S bond twisting, CF3rotation, phenyl twisting, PPh3rotation, and, in some cases, by coupled motions. The composite energy surface for each CO frequency group shows that interconversions among the low-energy structures are possible via both the direct and indirect pathways, while the indirect pathway via isomers in the νCO≈ 1980 cm–1group is more favorable, which is a result consistent with recent experimental work. This work provides the first complete mechanistic picture of the ultrafast isomerization of penta-coordinated, distorted SP, d6-transition-metal complexes.