Using London Dispersion Force Effects to Stabilize Inorganic and Organometallic Molecules

在化学系化学合成(SYN)计划的支持下，加州大学戴维斯分校化学系菲利普·鲍尔教授正在研究伦敦弥散(LD)效应在确定无机分子的结构和反应性方面的作用。化学键通常涉及两个原子之间的电子共享。这些键通常很强，是将许多化合物结合在一起的主要力量。然而，还有其他通常较弱的力量可以影响化合物的行为。其中之一被称为伦敦色散(LD)，它是由非键原子相互接近时瞬间产生的电偶极子造成的。虽然这些相互作用很弱，但它们可以稳定通常不稳定的化合物类别。这项研究提供了LD效应如何影响分子的细节，从而导致了违反直觉的结构和反应性。在化学品的制备过程中，这种相互作用通常没有被考虑到，但这个项目试图为在设计新分子中使用LD提供基础。该项目将为各种学生提供复杂的化学技术培训，包括来自代表性不足群体的学生。此外，还有一个面向K-12学生和教师的外联部分，其目的是增加未被充分代表的群体对科学的参与。这一提议的主要主题是研究伦敦色散(LD)能量对空间拥挤无机分子的结构、稳定性和反应性的影响。尽管这种相互作用的性质很弱(大约1kcal摩尔-1/H-H相互作用)，但这些作用仍然普遍存在，并且共同地可以强烈地影响分子的性质。最近的LD结果是使用三苯配体，其中两个侧翼芳环上的烷基取代产生接近的H-H方法来稳定LD力。然而，在三苯基配体中，H原子的数量是有限的，它们还可以通过侧翼环上的亲核相互作用进一步相互作用。为了克服这些限制，将制备在‘侧翼’位置上具有较少活性脂肪环或刚性碳氢骨架基团的配体。将探索这些配体形成和稳定目前未知的(A)有机铜(I)化合物，(B)具有过渡金属-主族元素键的化合物，(C)未络合的独立双烯和(D)新的LDF给体有机锂试剂的能力。此外，还将评估LD力在有机金属合成中的使用，例如在碱土中组装(E)双金属与金属烯和(F)金属-金属键合的络合物，以及早期过渡金属。这一知识预计将提供有关LD部队如何使新的复合班级聚集的有用信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemical Synthesis (SYN) Program of the Chemistry Division, Professor Phillip Power, Chemistry Department, University of California–Davis is studying the role of London dispersion (LD) effects in determining the structures and reactivity of inorganic molecules. Chemical bonds often involve the sharing of electrons between two atoms. These are bonds are typically quite strong and are the principal forces that hold many chemical compounds together. However, there are other, usually weaker forces that can influence the behavior of compounds. One of these is called London Dispersion (LD) and results from instantaneously generated electric dipoles that form when non bonded atoms approach one another. While these interactions are weak, they can stabilize normally unstable classes of compounds. The research provides details of how the LD effects can influence molecules leading to structures and reactivity that are counterintuitive. Such interactions have not generally been considered during the preparation of chemicals, but this project seeks to provide the groundwork to utilize LD in the design of new molecules. The project will provide training in sophisticated chemical techniques to a variety of students, including ones from underrepresented groups. In addition, there is an outreach component to K-12 students and teachers that aim to increase the participation of underrepresented groups in science. The main theme of this proposal is the investigation of the effects of the London Dispersion (LD) energies on the structures, stability, and reactivity of sterically crowded inorganic molecules. Despite the weak nature of such interactions (ca. 1 kcal mol-1 /H---H interaction) these are nonetheless ubiquitous and, collectively, can strongly influence molecular properties. Recent LD results have been obtained using terphenyl ligands in which alkyl substituents on two ‘flanking’ aryl rings generate the close H---H approaches for the LD force stabilization. However, in the terphenyl ligands the number of H atoms is limited and they also can interact further via nucleophilic interactions of their flanking rings. To overcome these limitations, ligands that have either less reactive aliphatic rings or rigid hydrocarbon framework groups at the ‘flanking’ positions will be prepared. The ability of these ligands to form and stabilize presently unknown (a) organocopper(I) compounds, (b) compounds with transition metal - main group element bonds, (c) uncomplexed, free-standing dialuminenes and (d) new LDF donor organolithium reagents will be explored. In addition, the use of LD forces in organometallic synthesis, for example, assembling (e) dimetallenes vs. metalylenes and (f) metal-metal bonded complexes in the alkaline earth, and early transition metals will be evaluated. This knowledge is expected to provide useful information on how LD forces enable the assembly of new compound classes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.