Unravelling the photochemistry of organometallic N-heterocyclic carbene complexes

N-杂环卡宾或NHC现在是过渡金属化学中非常常见的配体。M-NHC配合物作为金属强给电子体的能力使其在催化过程中得到了广泛的应用，在这些催化过程中，它们的性能往往优于类似的膦基催化剂。虽然强给电子体性质在热诱导化学计量反应中也被观察到是重要的，但关于M-NHC配合物的光化学反应只有一个报道（由该提案的一位研究人员），其揭示了与可比膦化学的显著差异。我们现在希望进行广泛的研究M-NHC光化学，结合两个研究小组的专业知识，使新的NHC化合物（浴），并通过快速时间分辨红外（TRIR）光谱检测中间体和动力学测定（Nottigham）来研究它们的光化学。我们的目标将是（a）跟进我们最初的论文，该论文涉及M-NHC二氢化物络合物（M-H2），并进行TRIR研究，以了解化学反应是如何发生的（即观察中间体，确定动力学），（B）观察M-NHC络合物附着到通常非常惰性的配体如稀有气体（如氙）上的能力，或者附着然后可能催化分解烷烃的能力，（iii）最后，探索供体NHC的存在是否会对称为激发态的通常寿命短的反应性分子的寿命和性质产生影响

N-heterocyclic carbenes or NHCs are now very common ligands in transition metal chemistry. Their ability to act as very strong donors to metals has resulted in the finding widespread applications in catalytic processes, where they often outperform analogous phosphine based catalysts.While the strong donor properties have also been observed to be important in thermally induced stoichiometric reactions, there has only been one report on the photochemical reactions of M-NHC complexes (by one of the investigators on this proposal), which revealed dramatic differences to the comparable phosphine chemistry. We now wish to undertake a wide ranging study of M-NHC photochemistry, combining the expertise of two research groups to make new NHC compounds (Bath) and study their photochemistry through the detection of intermediates and determination of kinetics (Nottigham) by fast time-resolved infra-red (TRIR) spectroscopy. Our targets will be (a) to follow up our initial paper which concerned M-NHC dihydride complexes (M-H2) with a TRIR study to understand how the chemistry takes place (i.e. seeing intermediates, determining kinetics), (b) to look at the ability of M-NHC complexes to attach to usually very inert ligands such as noble gases, like xenon, or attach and then perhaps break apart catalytically alkanes, (iii) and finally to probe whether having donor NHCs present makes a difference to the lifetimes and properties of typically short-lived, reactive molecules called excited states