Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Acc Chem Res. 2010 May 18;43(5):602-11. doi: 10.1021/ar9002027.
Computational and theoretical chemistry provide fundamental insights into the structures, properties, and reactivities of molecules. As a result, theoretical calculations have become indispensable in various fields of chemical research and development. In this Account, we present our research in the area of computational transition metal chemistry, using examples to illustrate how theory impacts our understanding of experimental results and how close collaboration between theoreticians and experimental chemists can be mutually beneficial. We begin by examining the use of computational chemistry to elucidate the details of some unusual chemical bonds. We consider the three-center, two-electron bonding in titanocene sigma-borane complexes and the five-center, four-electron bonding in a rhodium-bismuth complex. The bonding in metallabenzene complexes is also examined. In each case, theoretical calculations provide particular insight into the electronic structure of the chemical bonds. We then give an example of how theoretical calculations aided the structural determination of a kappa(2)-N,N chelate ruthenium complex formed upon heating an intermediate benzonitrile-coordinated complex. An initial X-ray diffraction structure proposed on the basis of a reasonable mechanism appeared to fit well, with an apparently acceptable R value of 0.0478. But when DFT calculations were applied, the optimized geometry differed significantly from the experimental data. By combining experimental and theoretical outlooks, we posited a new structure. Remarkably, a re-refining of the X-ray diffraction data based on the new structure resulted in a slightly lower R value of 0.0453. We further examine the use of computational chemistry in providing new insight into C-H bond activation mechanisms and in understanding the reactivity properties of nucleophilic boryl ligands, addressing experimental difficulties with calculations and vice versa. Finally, we consider the impact of theoretical insights in three very specific experimental studies of chemical reactions, illustrating how theoretical results prompt further experimental studies: (i) diboration of aldehydes catalyzed by copper(I) boryl complexes, (ii) ruthenium-catalyzed C-H amination of arylazides, and (iii) zinc reduction of a vinylcarbyne complex. The concepts and examples presented here are intended for nonspecialists, particularly experimentalists. Together, they illustrate some of the achievements that are possible with a fruitful union of experiment and theory.
计算化学和理论化学为分子的结构、性质和反应性提供了基本的见解。因此，理论计算在化学研究和开发的各个领域都变得不可或缺。在本综述中，我们介绍了我们在计算过渡金属化学领域的研究，通过实例说明理论如何影响我们对实验结果的理解，以及理论家和实验化学家之间的密切合作如何相互受益。我们首先研究了计算化学在阐明一些不寻常化学键细节方面的应用。我们考虑了二茂钛西格玛硼烷配合物中的三中心、二电子键和铑-铋配合物中的五中心、四电子键。还研究了金属苯配合物的键合。在每种情况下，理论计算都提供了对化学键电子结构的特殊见解。然后，我们给出了一个实例，说明理论计算如何帮助确定加热苯甲腈配位的中间配合物形成的κ(2)-N,N 螯合钌配合物的结构。基于合理的机理提出的初始 X 射线衍射结构似乎拟合得很好，R 值为 0.0478，显然可以接受。但是当应用 DFT 计算时，优化的几何形状与实验数据有很大的不同。通过结合实验和理论观点，我们提出了一个新的结构。值得注意的是，基于新结构重新精修 X 射线衍射数据导致 R 值略有降低，为 0.0453。我们进一步研究了计算化学在提供 C-H 键活化机制的新见解以及理解亲核硼酸酯配体的反应性方面的应用，解决了计算中的实验困难和反之亦然。最后，我们考虑了理论见解在三个非常具体的化学反应实验研究中的影响，说明了理论结果如何促使进一步的实验研究：（i）铜（I）硼酸酯配合物催化的醛二硼化反应，（ii）钌催化的芳基叠氮化物 C-H 胺化反应，以及（iii）锌还原乙烯基卡宾配合物。这里呈现的概念和实例是为非专业人士，特别是实验人员准备的。它们共同说明了通过实验和理论的有益结合可以实现的一些成就。
