Designing Enhanced Dispersion Force Effects Into Inorganic and Organometallic Molecules

化学部化学合成计划支持鲍尔教授的项目。鲍尔教授和他的团队正在开发新的化合物类别，以展示金属络合物中基团(配体)的相互作用。这些新化合物不同于目前已知的化合物，因为它们被设计为在分子之间显示增强的有吸引力的伦敦色散力(LDF)。伦敦弥散力加强了它们之间的结合，从而增强了它们延伸结构的稳定性。伦敦色散力描述的是分子之间的相互作用，而不是两个原子之间的相互作用(共价键)。到目前为止，这种作用力通常还没有被纳入到分子设计中。该项目的目的是从根本上了解如何在化学合成中操纵和利用这种力量。该项目位于无机、有机和有机金属化学的交界处。使用各种光谱、结构和计算技术来表征所获得的新化合物。除了合成方面的培训，该项目还让学生接触到各种物理化学和理论方法。该研究项目还包括旨在扩大少数族裔参与科学研究的推广活动。这项研究的基本科学目标是将增强的伦敦弥散力设计成分子，以便可以计算、测量它们的影响，并用于合成以前未知的分子类别。Power集团计划将重点放在烷基硼烷上，这些烷基硼烷的刚性碳氢取代基来自廉价的天然产品。他们已经证明，由于吸引人的伦敦色散力相互作用，扩展结构显示出与常规烷基硼烷非常不同的Lewis酸性。此外，Power小组还研究了受LDF强烈影响的主族和过渡元素中的各种歧化和离解反应。例如，合成了第一个稳定的双配位铜(II)衍生物。通常，低配位的铜(II)化合物由于自动还原为铜(I)物种或铜金属而不稳定。使用有利于LDF相互作用的配体，发生反向反应，自动氧化，从而从铜(I)起始材料获得稳定的双配位铜(II)物种。类似的效应使合成第一个双配位的钒(II)化合物成为可能。研究还表明，LDF效应对于多键重主族化合物是重要的，这种效应通常超过弱元素-元素键。LDF对众多多键重主族化合物的稳定性起着重要作用。本科生、研究生和博士后研究员通过该奖项获得支持。所获得的知识可能是我们理解成键以及如何构建更复杂结构的基础。

The Chemical Synthesis Program of the Chemistry Division supports the project by Professor Power. Professor Power and his group are developing new classes of compounds to demonstrate the interaction of the groups (ligands) within a metal complex. The new compounds differ from those currently known because they are designed to display enhanced attractive London Dispersion Forces(LDFs) between molecules. London Dispersion Forces strengthen the bonding and hence the stability of their extended structures. The London Dispersion Forces describe interactions between molecules rather than interactions between two atoms (covalent bonds). To date, such forces have not generally been incorporated into molecular design. The project is aimed at obtaining a fundamental understanding of how such forces can be manipulated and exploited in chemical synthesis. The project lies at the interface of inorganic, organic, and organometallic chemistry. A variety of spectroscopic, structural, and computational techniques are used to characterize the new compounds obtained. Besides training in synthesis, the project exposes students to a variety of physico-chemical and theoretical methods. The research project also includes outreach activities designed to broaden the participation of underrepresented minorities in scientific research.The basic scientific objective of the research is to design enhanced London Dispersion Forces into molecules so that their effects can be calculated, measured, and used to synthesize previously-unknown classes of molecules. The Power group plans to focus investigations on alkyl boranes with rigid hydrocarbon substituents derived from inexpensive natural products. They have already shown that the extended structures display Lewis acidic properties very different from regular alkyl boranes as a result of the attractive London Dispersion Force interactions. In addition, the Power group investigates a variety of disproportionation and dissociation reactions in both the main group and transition elements that are strongly influenced by LDF. Examples involve the synthesis of the first stable, two-coordinate copper(II) derivative. Normally, low-coordinate copper(II) compounds are unstable due to auto-reduction to copper(I) species or copper metal. Using a ligand that favors LDF interactions, the reverse reaction, auto oxidation, occurs so that a stable two-coordinate copper(II) species is obtained from a copper(I) starting material. A similar effect enables the synthesis of the first two-coordinate vanadium(II) compound. The investigations have also shown that LDF effects are important for the multiple-bonded heavier main group compounds, where such effects usually exceed the weak element-element bonding. LDFs are responsible for the stability of numerous multiple bonded heavier main group compounds. Undergraduates, graduate students, and post-doctoral fellows are supported through this award. The knowledge gained may be fundamental to our understanding of bonding and how more complex structures are built.