RUI: Theoretical Studies of Non-Covalent Interactions and Chemical Bonding Transitions Across Phases in Inorganic Systems, and Investigations of Other Modes of Weak Bonding

在这个由化学系化学结构动力学和机理(CSDM-A)计划资助的项目中，里士满大学的凯林·唐纳德教授正在使用理论方法来理解化学体系中分子之间的相互作用，其中特别重要的是弱相互作用。在现代化学中，众所周知，原子和分子可以以非常强的方式相互作用形成新的化合物，而以更容易逆转或破坏的弱方式相互作用。然而，对于后一种情况，即使交互作用相对较弱，它们也可以非常重要。例如，弱相互作用使壁虎能够爬墙，并在自然界和研究实验室中产生其他明显的影响。这个项目研究弱相互作用至关重要的几类化学体系。这类体系包括金属卤化物类化合物，它们形成由弱相互作用稳定的固体，在某些情况下，但在其他情况下不是。该项目在一定程度上致力于阐明为什么某些金属卤化物的固体在某些情况下只通过弱相互作用保持在一起，但这些弱相互作用被其他金属卤化物中更强大的力量所取代。重点是使用数学和计算工具来加深我们对弱相互作用如何转变为强化学键的理解，进而更好地预测新的和有趣的材料性质。该项目将吸引本科生和研究生参与教师指导的研究，为来自不同背景的高中生提供指导研究经验，并帮助他们获得对大学成功至关重要的学术技能。该项目在里士满大学(UR)凯林·唐纳德教授的指导下，旨在使成键转变现象合理化，在这种成键转变现象中，二卤化物二氟化汞等化学体系在齐聚过程中从团簇中的弱范德华类型键转移到极性共价单体间键，最终聚合到离子固体结构上。这些研究旨在阐明这一现象的基本基础和演变，它存在于其他重主族和d-块金属的卤化物、氢化物和氧化物中。唐纳德团队还将研究相对论效应在这些现象中的作用。这里研究的另一类弱相互作用是卤素键和其他所谓的西格玛空穴相互作用，它们继续与生物学和有机卤化物的晶体工程有关。这项工作的一个目标是促进对有机和无机卤化物以及其他体系中不寻常的成键模式的理解，如流动的有机金属和潜在的硼环化合物。Donald教授的本科生将完成大部分建议的工作，来自不同背景的高中生将参与Donald教授设计的研究/指导计划，该计划将专注于吸引来自代表性不足群体的高三学生和潜在的第一代大学生(I)在UR的研究实验室进行实践活动，(Ii)与UR专业人员就学习技能、压力管理和其他关键能力进行直接讨论，以及(Iii)暑期研究奖学金。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。

In this project funded by the Chemical Structure Dynamics and Mechanisms-A (CSDM-A) program of the Chemistry Division, Professor Kelling Donald of the University of Richmond is using theoretical methods to understand the interactions between molecules in chemical systems where particularly weak interactions are important. It is well-known in modern chemistry that atoms and molecules can interact with each other in very strong ways to form new compounds and in weak ways that can be more readily reversed or disrupted. For the latter case, however, even though the interactions are relatively weak, they can be very important. Weak interactions allow geckos to climb walls, for instance, and have other demonstrable effects in nature, and in research laboratories. This project investigates classes of chemical systems where weak interactions are crucial. Such systems include compounds of the metal halide class that form solids stabilized by weak interactions, in some cases, but not in other cases. The project is dedicated in part to elucidating why the solids of some metal halides are held together only by weak interactions in certain cases, but those weak interactions are overtaken by much more powerful forces in other metal halides. The focus is on using mathematical and computational tools to further our understanding of how weak interactions transition to strong chemical bonding and, in turn, to better predict new and interesting materials properties. This project will engage undergraduates and post-baccalaureate students in faculty-guided research and provide high school students from diverse backgrounds with mentored research experiences, and help them to acquire academic skills that are crucial for success in college.This project under the guidance of Professor Kelling Donald at the University of Richmond (UR) aims to rationalize the bonding transition phenomenon in which chemical systems such as the binary dihalide mercury difluoride, move during the oligomerization process from weak van der Waals-type bonding in clusters to polar covalent inter-monomer bonding, eventually converging upon an ionic solid structure. These studies are aimed at elucidating the fundamental basis and the evolution of this phenomenon where it exists among the halides, hydrides, and oxides of other heavy main group and d-block metals. The Donald group will also examine the role of relativistic effects in these phenomena. Another class of weak interactions under examination here is halogen bonding and other so-called sigma hole interactions, which continue to be implicated in biology and in the crystal engineering of organohalides. A goal in this work is to advance understanding of that phenomenon for organic and inorganic halides, and other unusual bonding modes in systems such as fluxional organometallic and potential ouroboric ring compounds. Professor Donald’s undergraduate students will perform the majority of the proposed work, and high school students from diverse backgrounds will participate in a research/mentoring program devised by Professor Donald, which will focus on attracting high school juniors from underrepresented groups and potential first-generation college students for (i) hands-on activities in research labs at UR, (ii) direct discussions with UR professionals on study skills, stress management, and other key competencies, and (iii) summer research fellowships.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.