Modulating the reactivity of uranyl by manipulating the O=U=O bond angle in uranyl ansa-type cyclopentadienyl complexes

锕系元素显示了元素周期表中最多样化的化学成分，其中关键的核燃料循环元素（U，Np和Pu）是最复杂的。在有氧条件下，+VI（U）和+V（Np）的氧化态占主导地位，这些formoxo放线菌离子AnO 22+与线性O=An=O键。虽然这些具有众所周知的广泛的配位化学，但最近发现的一些显着特征挑战了对锕基单元（这里是铀酰）的热力学稳定性和动力学惰性的传统观点和理解。锕系元素的氧化还原化学也很复杂;铀酰（V）离子容易发生氧化还原反应，这些反应涉及铀酰键的活化和氧原子转移反应，但这些过程的机制仍然不清楚。本计画的目的是探讨铀酰阳离子中的成键，借由强σ贡献及几何限制的柄型配位体来影响铀酰单元的反应性。这将改变它的电子结构和反应性，我们将通过发光光谱特别是探测它的氧化还原化学，包括氧原子转移反应，以了解在核回收和处置方案中发生的氧化还原过程。具体目标是：-从高价氧代前体合成一个新的与柄型Cp配体配位的铀酰（VI）配合物家族。-通过光学/振动光谱和DFT计算探测电子结构。研究柄型Cp铀酰配合物与O原子转移试剂进行氧原子转移反应的反应性。使用瞬态吸收和超快发射光谱法，使用紫外和可见光研究柄型Cp铀酰络合物的电子物理学。研究铀酰（V）衍生物的合成路线。

The actinide elements display some of the most diverse chemistry encountered anywhere in the Periodic Table, with the key nuclear fuel cycle elements (U, Np and Pu) being the most complex. In aerobic conditions, the +VI (U) and +V (Np) oxidation states dominates and these formdioxo actinyl ions AnO22+ with linear O=An=O bonds. While these have well known andextensive coordination chemistry, there are some remarkable features that have been recentlydiscovered challenging the traditional view and understanding of the thermodynamic stability andkinetic inertness of the actinyl unit (here, uranyl). The redox chemistry of the actinides is also complex;uranyl(V) ions are susceptible to disproportionation and these reactions involve activation of the uranyl bond and oxygen atom transfer reactions, yet the mechanisms for such processes remain unclear. This project aims to probe the bonding in the uranyl cation by employing strongly sigma donating and geometrically constrained ansa-type cyclopentadienyl ligands to influence the reactivity of the uranyl unit. This will alter its electronic structure and reactivity, where we will probe its redox chemistry by luminescence spectroscopy in particular, including oxygen atom transfer reactions, to understand redox processes that occur in nuclear recycle and disposal scenarios.Specific aims are to:- Synthesise a new family of uranyl(VI) complexes coordinated to ansa-Cp type ligands from high valent oxo precursors.- Probe of the electronic structure by optical/ vibrational spectroscopies and DFT calculations.- Investigate the reactivity of the ansa-Cp uranyl complexes for oxygen atom transfer reactions with O atom transfer reagents.- Investigate the photophysics of the ansa-Cp uranyl complexes using UV and visible light using transient absorption and ultrafast emission spectroscopies.- Investigate synthetic routes to uranyl(V) derivatives.