Unravelling the photochemistry of organometallic N-heterocyclic carbene complexes

N-杂环卡宾或NHC是过渡金属化学中非常常见的配体。它们作为非常强的金属给体的能力使其在催化过程中得到了广泛的应用，在催化过程中，它们的性能往往优于类似的磷化氢催化剂。虽然强施主性质也被观察到在热诱导的化学计量反应中很重要，但只有一篇关于M-NHC络合物的光化学反应的报告(由这一提议的一位研究人员)，这揭示了与可比的膦化学的巨大差异。我们现在希望对M-NHC的光化学进行广泛的研究，结合两个研究小组的专业知识来合成新的NHC化合物(Bath)，并通过快速时间分辨红外(TRIR)光谱检测中间体和测定动力学(Nottigham)来研究它们的光化学。我们的目标将是：(A)用TRIR研究来跟进我们最初关于MNHC二氢化合物(M-H2)的论文，以了解化学是如何发生的(即观察中间体，确定动力学)，(B)观察M-NHC化合物与通常非常惰性的配体(如惰性气体，如氙气)结合的能力，或者结合并可能催化分解烷烃的能力，(Iii)最后探索有施主NHC的存在是否会对通常被称为激发态的短寿命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 hemistry. 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 MNHC 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