Donor substituted alkynes as directional bridging ligands in polynuclear complexes

超分子配位化合物的显著性质突出了预期研究项目的背景，在超分子配位化合物中，特定的炔类配体确保了金属间的强烈耦合。不同金属中心的连接是由两个α-位上都带有给体基团的炔基配体完成的。三键上的侧向配位将原来的线型炔烃转变为kappa2-螯合配体。施主中心可以是硫族原子，也可以是烟原原子。具有末端给体基团的单核配合物可被视为功能配体。由于炔络合物部分的弯曲背角而产生的大咬合角、高的极化率和中间过渡金属的普遍氧化还原活性可能导致了一种非常规的配位行为。这些定向桥联配体对其多核配合物特性的具体作用将通过供体中心的系统变化来阐明。该研究项目的主要主题是开发可控和分步骤制备具有α-供体中心的炔类多核配合物的合成策略。反过来，这一目标又依赖于通过亲核取代直接从相应的W(II)或W(IV)乙炔或卤代乙炔配合物中获得具有自由末端给体的炔烃配合物。配位炔上的这种取代反应只是零星的，没有系统的研究。除了组装多核配位化合物外，这一策略还有可能合成原本难以制造的炔烃。对所得到的多核配合物的电子结构进行了光谱和理论的综合研究。在此基础上，将对这些新型配体系统的潜在应用进行比较分类和评价。

The background of the intended research project is highlighted by the remarkable properties of supramolecular coordination compounds, in which specific alkyne ligands ensure strong intermetallic coupling. The linkage of different metal centers is accomplished by alkyne ligands, which bear donor groups in both alpha-positions. Side-on coordination at the triple bond turns the primarily linear alkynes into kappa2-chelate ligands. The donor centers can be a chalcogen- or a pnicogen atom. Mononuclear complexes with terminal donor groups may be regarded as functional ligands. The large bite angles due to the bend back angle in the alkyne complex moiety, the high polarizability and the prevalent redox activity of alkyne complexes with mid transition metals may lead to an unconventional coordination behavior. The specific function of these directional bridging ligands for the characteristics of their polynuclear complexes will be elucidated by a systematic variation of the donor centers.The main topic of the research project is the development of synthetic strategies for the controlled and stepwise preparation of polynuclear complexes featuring alkynes with alpha-donor centers. In turn, this goal depends on a straightforward access to alkyne complexes with free terminal donors from corresponding W(II)- or W(IV) acetylene or halogenacetylene complexes via nucleophilic substitution. Such substitution reactions on the coordinated alkyne were only sporadically and not systematically investigated. In addition to the assembling of polynuclear coordination compounds, the synthesis of otherwise difficult to make alkynes might be possible by this strategy. The electronic structures of the obtained polynuclear complexes will be comprehensively studied by spectroscopy and theory. On this basis a comparative classification and evaluation with respect to potential applications of these novel ligand systems will be accomplished.