Novel reactivity of low oxidation state main group compounds

在过去的几十年里，主基团化学取得了重大进展。近年来报道了大量极不寻常的分子主族化合物，挑战了我们对化学键和元素-元素相互作用的理解。许多这些分子（或混合物）已被发现包含不寻常的键模式和高能电子构型的组合，通常与空轨道和空配位位点结合在一起。此外，许多物种表现出相对较小的HOMO-LUMO隙和/或甚至具有较小的单重态-三重态能隙。因此，这些类型的分子表现出独特的反应性，其中一些能够激活相对惰性的分子。这种新的反应性可以发展成新的反应，甚至催化方案。许多新的主族元素都是低氧化态化合物。它们的反应活性与高能电子态和低氧化态元素的前沿轨道构型直接相关。为了获得高度新颖的低氧化态主基化合物，需要开发合适的配体体系，并将其用于这些物质的稳定。电子和空间要求都非常重要，通常配体系统的细微变化会导致非常不同的结果。本项目将探索2族、13族和14族元素的新型低氧化态化合物的合成和表征，并研究这些物种的性质和反应性。为此，我们将使用、设计和开发一系列立体要求高的配体，并研究它们稳定新型低氧化态主基化合物的能力。根据我们之前使用的化合物类别，我们将使用一系列亚磷磷烷、磷酰胺、双氯胺酸盐和其他中性和阴离子给体配体。通常，合适的配体前体与主族元素起始材料反应形成典型的异亲性元素化合物，并可以研究这些物种的还原化学。由此产生的新型低氧化态化合物的化学性质将用于对一系列（小）分子（包括工业相关化合物）的异常活化反应进行研究。我们的目标是不寻常的和新颖的-和-键激活，并将这些发展成新的反应和可能的新的催化转化。反应监测将主要通过多核核磁共振波谱进行，分离化合物的化合物表征将通过多核核磁共振波谱、x射线晶体学、红外光谱、元素分析、质谱和其他合适方法的分析技术相结合来实现。为此，圣安德鲁斯大学化学学院拥有一系列最先进的分析和光谱实验室和服务，并拥有在化学科学方面具有广泛专业知识的国际领先研究小组。学生将学习有关空气和水分敏感和可能热不稳定的分子主基团配合物的合成、分离和表征的各种技术，以及专门的有机配体系统和一些无机固体的技术。处理技术将包括施伦克线和手套箱技术在干燥的惰性气体结合专业玻璃器皿和现代实验室设备。学生将进一步加深对样品制备的知识和技能，包括为一些分析技术（如核磁共振光谱、红外光谱）获取光谱数据的一些实践培训，以及如何为其他分析工具准备和提交样品。此外，在实验室环境中安全工作，实验室组织，研究计划，相关文献知识，演示，报告和写作技能等专业知识将得到提高。

Main group chemistry has seen significant advances over the past few decades. A plethora of highly unusual molecular main group compounds has been reported in recent years that challenge our understanding of chemical bonding and element-element interactions. Many of these molecules (or mixtures) have been found to contain a combination of unusual bonding modes and a high energy electronic configuration that is often combined with vacant orbitals and empty coordination sites. Many species furthermore show relatively small HOMO-LUMO gaps and/or even possess a small singlet-triplet energy gap. As a consequence, these types of molecules show a unique reactivity and some are capable of activating relatively inert molecules. This novel reactivity can be developed into new reactions and even catalytic protocols. Many of these novel main group element species are low oxidation state compounds. Their reactivity is directly related to the high energy electronic state and the frontier orbital configuration of the low oxidation state element. To access highly novel low oxidation state main group compound, suitable ligand systems need to be developed and employed in the stabilization of those species. Both the electronic and steric requirements are highly important, and often subtle changes of the ligand system can lead to very different outcomes. This projects will explore the synthesis and characterization of novel low oxidation state compounds of group 2, 13 and 14 elements and study the properties and reactivity of these species. To this end, we will use, design and develop a range of sterically demanding ligands and study their ability to stabilize novel low oxidation state main group compounds. Based on previously used compound classes within our group, a range of iminophosphorane, phosphinoamide, Bdiketiminate and other neutral and anionic donor ligands will be employed. Often, suitable ligand precursors are reacted with main group element starting materials to form typically heteroleptic element compounds and the reduction chemistry of those species can be investigated. The chemistry of the resulting novel low oxidation state compounds will be studied for unusual activation reactions towards a range of (small) molecules including industrially relevant compounds. We target the unusual and novel activation of - and -bonds and will develop these into new reactions and possibly novel catalytic transformations. Reaction monitoring will be predominantly carried out by multinuclear NMR spectroscopy, compound characterization of isolated compounds will be achieved by a combination of analytical techniques including multinuclear NMR spectroscopy, X-ray crystallography, IR spectroscopy, elemental analysis, mass spectrometry and other suitable methods. To this end, the School of Chemistry at the University of St Andrews runs a series of state-of-the-art analytical and spectroscopic laboratories and services, and houses internationally leading research groups with a wide expertise in the chemical sciences.The student will learn various techniques regarding the synthesis, isolation and characterization of air and moisture sensitive and possibly thermally unstable molecular main group complexes, as well as those of specialized organic ligand systems and some inorganic solids. Handling techniques will include Schlenk line and glove box techniques under dry inert gas in combination with specialized glassware and modern laboratory equipment. The student will further deepen his knowledge and skills for the preparation of samples including some hands-on training for acquiring spectral data for some analytical techniques (e.g. NMR spectroscopy, IR spectroscopy) and how to prepare and submit samples for other analytical tools. In addition, safe working in a laboratory environment, laboratory organization, research planning, knowledge of relevant literature, presentation, reporting and writing skills and other expertise will be improved upon.