SusChEM: Theoretical Studies of Inorganic, Organometallic, and Bioinorganic Systems

在这个由化学系化学结构、动力学和机理B计划资助的项目中，德克萨斯农工大学的迈克尔·B·霍尔教授利用现代计算技术研究了催化化学中的重要问题。该项目研究自然产生的氢酶和相关的模型复合体，因为这些系统有望以低成本取代昂贵的铂电极，而铂电极现在用于开发氢作为一种能源。更多的研究是关于通过与廉价的金属催化剂而不是贵金属反应来激活和形成化学键，这一发展对化学工业很重要。除了为德克萨斯农工大学的学生和博士后提供教育外，许多实验合作者还将教育方面带给了更广泛的受众。由霍尔教授领导的分子模拟实验室为校园内的研究人员提供了访问最新的原子模拟软件和硬件的途径。该实验室还支持在世界范围内免费分发芬斯克-霍尔法。这种方法具有简单的图形用户界面和在笔记本电脑上运行大型过渡金属计算的能力，使其易于被广泛的受众使用，并被纳入教学课程。采用非局域密度泛函理论(DFT)和从头算能量计算的全梯度几何构型优化，主要是团簇耦合、完全活性空间和多参考构型相互作用，正被用来解决目前无机、有机金属和生物无机化学中感兴趣的问题。具体的体系包括：(1)烯烃中的非无辜硫代配体和氢活化，其中金属-硫pi键足够弱，使得DFT无法处理实质性的多重引用特征；(2)钴催化的硼化反应(与Paul Chirik合作)，其中需要开发丰富的第一过渡排金属作为催化剂，但其机理似乎不同于第二过渡排金属的反应；(3)镍膦络合物中出人意料的非无辜行为(与Morris Bullock合作)，其中众所周知有助于提供质子还原质子的配体在其他转化中变得活跃；(4)未活化的SP3碳氢键的区域选择性官能化；(5)氟烷烃歧化反应(与Tom Baker合作)，其中金属环的形成和稳定性与其进一步转化为最终复分解产物竞争；(6)镍铁氢酶研究以包括更多的蛋白质主链，在文献中仍有几种竞争机制，但没有对官能团进行充分的校准；(7)模拟新的镍铁氢酶及其突变体(与David Barondeau合作)，其中桥式羰基附近残基的变化改变反应活性；以及(8)氢酶合成模型(与Marcetta Darensburg合作)，其中新配体的探索打开了意想不到的新机制。

In this project funded by the Chemical Structure, Dynamics, and Mechanisms B Program of the Division of Chemistry, Professor Michael B. Hall at Texas A&M University, College Station, investigates important problems in catalytic chemistry by using modern computational techniques. The project studies the naturally occurring hydrogenase enzymes and related model complexes, as these systems hold promise for low-cost replacements for expensive platinum electrodes that are now used for the development of hydrogen as an energy resource. Additional studies are on the activation and formation of chemical bonds by reactions with inexpensive metal catalysts rather than precious metals, developments that are important for the chemical industry. In addition to the education of students and postdoctoral associates at Texas A&M University, a number of experimental collaborators bring the educational aspects to a broader audience. The Laboratory for Molecular Simulation, directed by Professor Hall, provides researchers across campus with access to the latest atomistic modeling software and hardware. The Laboratory also supports the free world-wide distribution of the Fenske-Hall method. This method, with its simple graphical user interface and ability to run large transition metal calculations on a laptop, allows it to be easily used by a wide audience and to be incorporated into teaching courses. Full-gradient geometry optimizations with non-local density-functional theory (DFT) and ab initio energy calculations, primarily coupled cluster, complete active space and multireference configuration interaction, are being used to solve problems of current interest in inorganic, organometallic, and bioinorganic chemistry. Specific systems include: (1) non-innocent thiolate ligands in alkene and hydrogen activation, where the metal-sulfur pi bonding is sufficiently weak, such that the substantial multireference character cannot be handled by DFT; (2) cobalt catalyzed borylation reactions (in collaboration with Paul Chirik), where development of abundant first-transition-row metals as catalysts are needed, but where the mechanism appears to be different from those for second-transition-row metals; (3) unexpected non-innocent behavior in nickel phosphine complexes (in collaboration with Morris Bullock), where the ligands that are well known to assist in providing protons for proton reduction become active in other transformations; (4) regioselective functionalization of unactivated sp3 carbon-hydrogen bonds; (5) fluoroalkane metathesis (in collaboration with Tom Baker), where the formation and stability of the metallocycle competes with its further transformation to the final metathesis products; (6) Nickel iron hydrogenase studies to include more of the protein backbone, where there are still several competing mechanisms in the literature, but where there is insufficient calibration of the functionals; (7) modeling new nickel iron hydrogenases and their mutants (in collaboration with David Barondeau), where changes in the residues near the bridging carbonyl site change the reactivity; and (8) hydrogenase synthetic models (in collaboration with Marcetta Darensbourg), where exploration of new ligands opens up unexpected new mechanisms.