Chemical Bonding Across the Periodic Table

罗尔德·霍夫曼的研究得到了大分子、超分子和纳米化学项目的支持，该项目将化学和物理方法结合起来，预测元素周期表中的新结构、性质和反应性，特别是在极端压力条件下的物质。正在探索的问题涵盖了从氢到砹的所有化学领域。在高压领域，这项工作正在探索SiO（不熟悉的石英，SiO2）的可能稳定性，以及AuO（在结构中两种形式的金之间具有所谓的混合价跃迁）和Li-或h -掺杂NbN等多种物质在压力下对分子乙炔和二茂铁的潜在超导性。为了进一步了解分子和宏观之间的世界，该工作正在探索低维CdSe和NaCl阵列中极性和维度的相互作用，研究如何稳定石墨烯的硅类似物，并探索潜在的金属胶束。由于预测是对理解的最佳测试，该研究开始设计尚未形成的分子和扩展系统，包括一些非经典有机金属，非典型有机碘化物，包含四面体和方平面主基团原子的新型网络，以及氧化物中O-O键的可能形成。化学是在原子和分子的持久组合的性质中发现的。在化学艺术、工艺、商业和科学的中心，从它们多变的组合中产生了令人难以置信的有机和无机化学的多样性。走出这个中心，人们会遇到更丰富的生物功能和具有不同寻常特性的材料，因为化学接触并影响着世界的其他部分。分子科学继续在一个分子的形状，另一个分子的反应性，第三个分子的不寻常的电或磁特性上给人惊喜。但是我们有办法去理解，就像化学家在创造新事物的过程中利用经验那样，既定性又富有成效。拟议的研究解决了这种理解的需要，特别是在地球中心等压力下物质的行为（在一些实验室也可以实现）。该提案解决了元素周期表上的一系列键合情况，从氢到锕系元素，该提案使用相当特定的键合谜题作为跳板，构建理解框架，化学家和物理学家可以从中提取并自己设计新的分子和新的扩展结构（在矿物，钻石，金属中发现的类型）。这些分子可能具有有趣而重要的特性，高温超导性只是其中之一。对分子和扩展系统及其结构和性质的存在进行有风险的、具体的预测——这是对化学真正理解的最好测试，也是所从事工作的一个标志。

Roald Hoffmann is supported by the Macromolecular, Supramolecular and Nanochemistry Program in research that melds chemical and physical approaches to the prediction of new structures, properties and reactivity across the periodic table, and especially matter under extreme conditions of pressure. The problems being explored range across all of chemistry, from hydrogen to astatine. In the realm of high pressure, the work is exploring the possible stability of SiO (not familiar quartz, SiO2), the potential superconductivity of species as diverse as AuO (with a so-called mixed valence transition between two forms of gold in the structure), and Li- or H-doped NbN, to molecular acetylenes and ferrocene under pressure. In order to gain further insight into the world in-between the molecular and the macro, the work is exploring the interplay of polarity and dimensionality in low-dimensional CdSe and NaCl arrays, looking at how to stabilize the silicon analogue of graphene, and exploring potential metallic micelles. Since prediction is the best test of understanding, the research sets out to design as yet unmade molecular and extended systems, including some nonclassical organometallics, untypical organoiodides, novel networks containing both tetrahedral and square-planar main group atoms, and the possible formation of O-O bonds in oxides.Chemistry is to be found in the properties of persistent groupings of atoms, of molecules. From their changeable combinations comes the incredible variety of organic and inorganic chemistry at the center of the art, craft, business and science of chemistry. And moving out from this center one encounters the still greater richness of biological function and materials with unusual properties, as chemistry touches and affects the rest of the world. The molecular science continues to surprise in the shape of one molecule, in the reactivity of another, in the unusual electric or magnetic properties of a third. But we have a way to go to understanding, in the qualitative yet productive way chemists have of parlaying experience into the making of the new. The proposed research addresses this need for understanding, especially in the behavior of matter under pressures such as those at the center of the earth (attainable in a few laboratories as well). Addressing a range of bonding situations across the periodic table, from hydrogen to the actinides, this proposal uses quite specific bonding puzzles as a springboard to build frameworks of understanding that chemists and physicists can take away and themselves design new molecules and new extended structures (of the type found in minerals, diamond, metals). Such molecules might have interesting and important properties, high temperature superconductivity just one of them. Risky, specific, predictions of the existence of molecules and extended systems, and their structures and properties -- the best test of real understanding in chemistry is a hallmark of the work being performed.