Synthesis, Reactivity and Catalysis of New Metallacarborane complexes

碳硼烷、硼烷和金属碳硼烷具有有趣的结构，并且在整个化学中对键的新见解和基本理解方面处于发展的前沿。本课题研究了新型早过渡镧系元素和主族元素金属硼烷的合成及其化学性质。该项目将在三个具体领域进行研究；在这些研究中的第一个，我们希望开发主基团碳硼烷衍生物，重点是反应性关系，旨在更好地了解这些不寻常化合物的化学性质。特别感兴趣的是新的13/14族主族元素配合物的化学，以及探索这些和相关碳硼烷衍生物在催化中的潜在应用。第二类研究集中于合成新的高氧化态的金属碳硼烷型的早期过渡元素和镧系元素衍生物，它们与已知的亚胺和环戊二烯类配合物有细微的相似之处。一些即将合成的新材料有望具有有趣的物理性质，可能包括理想的电子和/或光谱性质，有些将成为合成有趣材料的有用前体。尽管许多这些系统已经被发现了一段时间，但对这种化学反应形成金属酰胺、金属烷基和金属氢化物的开发却令人惊讶地不发达。即使从已知的材料开始，我们也有机会开发出非凡的复合物，其反应性从未被探索过，而且开发时机已经成熟。图1显示了一种可能的途径来开发含有二碳内酯配体和两个酰胺基团的Ti（IV）体系。这种{Ti（二碳内酯）}片段，或布谷鸟配合物，有可能作为替代地球丰富的金属，如Ca，并有望显示出与真正的配合物类似的反应活性，如Ca(HMDS)2和Ca(CH{SiMe3}2)2，两者都显示了在一系列催化应用中的应用，包括但不限于，聚硅氮烷合成。催化胺化反应和催化硼化反应。然而，与裸露的钙离子不同，金属双核内酯片段可以通过增加双核内酯配位面上的B和c取代基来进一步调谐，这样可以加入为系统提供电子密度的稳定基团。第三，作为我们研究的一部分，我们建议研究由二碳内酯配体支持的异金属体系的使用。我们将形成双金属配合物，其中外金属将对这些配合物表现出协同作用，改变它们的反应性和增强活性，正如Ae元素可以改变（13族和Ln元素也感兴趣），1族金属可以从Li变成Na， K， Rb等或非配位阳离子，如PPN （Ph3P=N=PPh3）。本研究所研究的金属碳硼烷簇在催化和分子电子学方面具有潜在的应用前景。该项目将重点放在新复合物的合成和表征上，这些新复合物与该系/大学和EPSRC的许多战略主题保持一致，使其成为培养学生的绝佳项目。

Carboranes, boranes and metallacarboranes have interesting structures and have been at the forefront of the development in new insights and fundamental understanding of bonding throughout chemistry. This project is concerned with the synthesis and chemical properties of new early transition/lanthanide element and main group element metallacarboranes. This project will pursue studies in three specific areas; In the first of these studies we wish to develop main group carborane derivatives, with an emphasis on reactivity relationships aimed at a greater understanding of the chemistry of these unusual compounds. Of particular interest is the chemistry of novel group 13/14 main group element complexes, as well as exploration of potential applications of these and related carborane derivatives in catalysis. The second category of studies is focused on an effort to synthesize new high oxidation state early transition element and lanthanide element derivatives of the metallacarborane type, which bear subtle resemblance to known imido and cyclopentadienide complexes. Some of the new materials which will be synthesized are expected to have interesting physical properties possibly including desirable electronic and/or spectral properties, and some will be useful precursors for the synthesis of interesting materials. Despite many of these systems having been known for some time, exploitation of this chemistry wrt the formation of metal amides, metal alkyls and metal hydrides is amazingly underdeveloped. Even starting form known materials we have the opportunity to develop remarkable complexes the reactivity of which has never been explored and is ripe for development. Figure 1 shows one possible route to the development of a Ti(IV) system incorporating a dicarboloide ligand and two amide groups this {Ti(dicarbollide)} fragment, or Cuckoo complex, has the potential to act as a surrogate earth abundant metal such as Ca and hopefully displaying similar reactivitys to real complexes such as Ca(HMDS)2 and Ca(CH{SiMe3}2)2, both of which have shown application in a range of catalytic applications including, but not limited to, polysilazane synthesis, catalytic hydroamination, and catalytic hydroboration. Hoverer unlike a naked Ca ion the metal dicarbollide fragment can be further tuned by augmentation of the B and c substituents on the coordinating face of the dicarbollide, such that stabilising groups which provide electron density to the system may be incorporated. Thirdly, as part of our study we propose to investigate the use of heterometallic systems supported by the dicarbollide ligand. We will form bi-metallic complexes in which the exo-metal will display a synergistic effect on these complexes modifying their reactivity and enhancing activity, and just as the Ae element can be changed (group 13 & Ln elemental are also of interest) the group 1 metal can be changed from Li to Na, K, Rb etc. or non-coordinating cations such as PPN (Ph3P=N=PPh3).The metal carborane clusters studied in this research may have potential applications in catalysis, and molecular electronics. The project incorporates a strong emphasis on synthesis, characterization of new complexes which align to a number of the strategic themes of the department/university and EPSRC, making it an excellent project for training students.