„Copper(I) boryl complexes: From Reactivity Studies on Catalytic Intermediates to Versatile Boryl Ligand Sources

铜（I）硼基络合物是铜催化的硼基化反应中与乙硼烷（4）衍生物的反应性中间体。然而，对这些反应的实验机理研究很少。少数现有研究使用单核和线性铜络合物[（IDipp）Cu-Bpin]作为催化剂模型（IDipp = 1，3-双（2，6-二异丙基苯基）咪唑-2-亚基，pin =（OCMe 2）2）。在初步的研究中，我们表明，这种复杂的空间要求IDipp配体是不典型的铜（I）硼络合物在典型的催化条件下存在的代表。对于通常采用的，空间要求较低的NHC和膦配体双核双硼基桥接络合物是主要的。然而，相关硼基配合物的结构取决于辅助配体以及硼基配体的性质。本研究项目的中心目标是系统地研究这些铜硼基配合物的反应性作为硼基以及辅助配体的函数，因此，配合物的结构。作为辅助配体，将使用各种NHC和膦配体，而不同的二烷氧基和二氨基硼基配体将被采用，如在初步研究中建立的。这项研究的核心是化学计量的研究，以及选定的代表性基板的反应性，重点是本中间体的NMR光谱和结构表征。这些结果将有助于对铜催化硼化反应的基本理解，从而为铜催化硼化反应作为合成工具的进一步合理发展做出贡献。此外，将对低价铜硼基络合物进行比较和类似反应性研究;通常作为铜（I）硼基络合物的分解产物产生的物质。对这些物种的了解对于该领域的合理进一步发展至关重要。此外，将对较重钴金属银和金的硼基络合物进行类似的反应性研究。然而，作为第一步，有必要合成具有不同辅助配体的银和金硼基络合物。然后，这些配合物将用于建立同源钴金属硼基配合物之间的差异和相似性。最后，在一个更探索性的尝试，使用铜（I）硼基配合物作为过渡金属配合物的硼基配体的来源将进行调查。这应该会产生新颖的、以前无法获得的硼基配合物，并将为全新的可能性开辟道路。

Copper(I) boryl complexes are well established reactive intermediates in copper catalysed borylation reactions with diborane(4) derivatives. Experimental mechanistic investigations on those reactions are, however, scarce. The few existing studies use the mononuclear and linear copper complex [(IDipp)Cu–Bpin] as catalyst model (IDipp = 1,3-bis(2,6-diisopropyl¬phenyl)imidazol-2-ylidene, pin = (OCMe2)2). In preliminary studies we showed that this complex with its sterically demanding IDipp ligand is not representative for the copper(I) boryl complexes present under typical catalytic conditions. With the typically employed, less sterically demanding NHC and phosphine ligands dinuclear bis-boryl bridged complexes are predominant. The structure of the relevant boryl complexes, however, depends on both the properties of the auxiliary ligand as well as the boryl ligand. The central aim of this research project is the systematic study of the reactivity of those copper boryl complexes as a function of the boryl as well as auxiliary ligand and, hence, the structure of the complex. As auxiliary ligands a variety of NHC and phospine ligands will be used, whereas different dialkoxido- and diaminoboryl ligands will be employed, as established in the preliminary studies. Central to this study are stoichiometric studies of the reactivity of well selected representative substrates with a focus on the NMR spectroscopic and structural characterisation of the present intermediates. The results will contribute to a fundamental understanding and consequently the rational further development of copper catalysed borylation reactions as synthetic tools. In addition comparative and analogous reactivity studies will be conducted on low-valent copper boryl complexes; species typically produced as decomposition products of copper(I) boryl complexes. The understanding of those species is crucial for a rational further development of the field. Furthermore, similar reactivity studies on the boryl complexes of the heavier coinage metals silver and gold will be conducted. As a first step, however, it is necessary to make silver and gold boryl complexes with different auxiliary ligands synthetically available. Those complexes will then be used to establish differences and similarities among the homologous coinage metal boryl complexes. Last, in a more explorative attempt, the use of copper(I) boryl complexs as a source of boryl ligands for transition metal complexes will be investigated. This should lead to novel, previously not accessible boryl complexes and will as such open the way to fundamentally new possibilities.