Redox-active Metalladiphosphine Ligands for Catalysis

本研究计划的主要课题是开发和利用具有氧化还原活性的基于炔的双膦配体，其被膦基团取代。在两个α-位上都带有P-原子的炔是优良的桥连配体。炔桥的不饱和特征涉及所连接的金属的高电子协同性，这在侧边碳膦螯合物配位模式中特别强。双核配合物中的这种协同性允许快速的分子内电子转移或甚至在两种金属上的离域状态。因此，从学术角度来看，这些配合物中的特定电子结构是一个有趣的研究问题。金属-乙炔二膦配体及其配位化学的系统发展旨在通过所涉及的金属的电子偶联来改善催化活性P，P-配位金属的催化活性。氧化还原活性膦提供了通过分子内电子转移（中继功能）在催化循环内切换供体强度的可能性，或者作为氧化加成的电子储存器和作为还原消除的接收器。后者是特别有趣的第一行过渡金属，以克服一个电子的氧化还原步骤限制。此外，在此基础上，顺磁性催化体系可能变得容易获得，由于它们作为强场配体的特性，它们通常与标准膦组合是抗磁性的。这种实际上远顺磁性对催化过程的影响属于该项目的中心问题。因此，具有末端膦基团的炔络合物是潜在的功能配体;并且其在催化中的使用通常是有希望的。

The main topic of the research proposal is the development and utilization of redox-active diphosphine ligands based on alkynes, which are substituted by phosphine groups. Alkynes bearing P-atoms in both alpha-positions are excellent bridging ligands. The unsaturated character of the alkyne bridges involves a high electronic cooperativity of the linked metals, which is particularly strong in the side-on carbon phosphine chelate coordination mode. Such cooperativity in dinuclear complexes allows either fast intramolecular electron transfers or even delocalized states over both metals. Accordingly, from an academic prospective the specific electronic structure in those complexes is an intriguing matter of investigation. The systematic development of metalla-acetylenediphosphine ligands and their coordination chemistry is directed to an improvement of catalytic activity of catalytically active P,P-coordinated metals by the electronic coupling of the metals involved. Redox-active phosphines offer the possibility to either switch the donor strength within the catalytic cycle by an intramolecular electron transfer (relay function) or to serve as an electron reservoir for oxidative addition and as a sink for reductive elimination. The latter is particularly interesting for first row transition metals in order to overcome the one-electron redox step limit. In addition, on this basis paramagnetic catalytic systems might become accessible, which are usually diamagnetic in combination with standard phosphines due to their character as strong field ligands. The kind of impact of this virtually distal paramagnetism on the catalytic processes belongs to the central issues of the project. Accordingly, alkyne complexes with terminal phosphine groups are potentially functional ligands; and the use of which in catalysis is generally promising.