QM/MM Approach to Isomerization of Ruthenium(II) Sulfur Dioxide Complex in Crystal; Comparison with Solution and Gas Phases
QM/MM Approach to Isomerization of Ruthenium(II) Sulfur Dioxide Complex in Crystal; Comparison with Solution and Gas Phases
复制标题
晶体中二氧化硫钌络合物异构化的 QM/MM 方法
DOI：
10.1021/acs.jpcc.8b04774
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
Shinji Aono and Shigeyoshi Sakaki
中科院分区：
文献类型：
--
作者：
D. Charczun;G. Kowzan;A. Nishiyama;A. Cygan;R. S. Trawinski;D. Lisak;P. Maslowski;Shinji Aono and Shigeyoshi Sakaki
分子晶体中化学反应的理论研究是一个具有挑战性的研究课题。为了优化晶体中的过渡态，我们改进了晶体模型，并在周期MM晶体模型的基础上改进了量子力学/分子力学（QM/MM）方法。由于钌（II）二氧化硫配合物[RuII（NH3）4（SO2）Py]2+ 1 Py具有两种可分离的亚稳结构，η1-O-键合MS 1和η2-S，O-键合MS 2，在低温条件下，GS经光辐照后，除了η1-S束缚基态GSin外，还形成了MS 2和MS 1（10-100 K），升高温度，发生从MS 2到MS 1和从MS 2到GS的热异构化。为了进行比较，采用三区三维参考位相互作用模型自洽场（RISM-SCF）方法研究了[RuII（NH3）4（SO2）L]n+（L= Cl-，W，andPy）在气相和水相中的热异构化反应.在气相中，MS 2对L = Cl-比MS 1稳定，但对L = W和Py稳定性较差。热异构化的发生具有类似的几何和电荷分布的变化L = Cl-，W，和Py，而L = Cl-的能量分布与L =WandPy的能量分布非常不同。在水相中，由于MS 1的溶剂化自由能较小，因此MS 1的稳定性远低于MS 2，并且对于L = Cl-、W和Py，RuII配合物的能量按照MS 1> MS 2> GS的顺序变得较低。在晶体中，1 Py的能量也按照MS 1> MS 2>GS的顺序降低。MS 1 → MS 2异构化的活化能远小于MS 2 → GS晶相的活化能，这与实验结果一致。在晶体中，目标QM分子的SO2与相邻Ru配合物之间的短程空间排斥作用以及目标QM分子与MM晶体之间的长程ES相互作用对决定MS 1和MS 2的相对稳定性以及热异构化的能垒起着至关重要的作用。
The theoretical study of chemical reactions in molecular crystals is a challenging research target. To optimize the transition state in a crystal, we have improved the crystal model and modified the quantum mechanics/molecular mechanics (QM/MM) method based on the periodic MM crystal model. We applied this method to the ruthenium(II) sulfur dioxide complex [RuII(NH3)4(SO2)Py]2+1Pywhich is potentially useful for optical data storage systems in crystal because this Ru complex has two isolable metastable structures, η1-O-boundMS1and η2-S,O-boundMS2, in addition to η1-S-bound ground stateGSin crystal.MS2andMS1are formed fromGSby photoirradiation at low temperature (10–100 K) and thermal isomerization occurs fromMS2toMS1and fromMS2toGSby raising the temperature. For comparison, the thermal isomerization of [RuII(NH3)4(SO2)L]n+(L= Cl–,W, andPy) was investigated in gas and aqueous phases, where the three-regions 3D reference site interaction model self-consistent field (RISM-SCF) method was employed to incorporate solvation effects in the aqueous phase. In the gas phase,MS2is more stable thanMS1forL= Cl–but less stable forL=WandPy. Thermal isomerization occurs with similar changes in geometry and charge distribution amongL= Cl–,W, andPy, whereas the energy profile ofL= Cl–differs very much from those ofL=WandPy. In the aqueous phase,MS1becomes much less stable thanMS2and the RuIIcomplex becomes lower in energy following the orderMS1>MS2>GSforL= Cl–,W, andPybecause of the small solvation free energy forMS1. In crystal,1Pyalso becomes lower in energy following the orderMS1>MS2>GS. TheMS1→MS2isomerization occurs with much smaller activation energy than theMS2→GSin crystal phase, which is consistent with the experimental observations. In crystal, the short-range steric repulsion between the SO2of the target QM molecule and the neighboring Ru complex and the long-range ES interaction between the target molecule and the MM crystal play crucially important roles in determining the relative stabilities ofMS1andMS2and the energy barrier of the thermal isomerization.