Sterically and electronically modified pyridines as ligands for the stabilization of reactive main group element compounds

本研究的目的是发展空间和电子修饰的吡啶类配体，用于稳定活性主族元素化合物。吡啶2，6-位的2，6-位与正电性二氮杂硼基基团的官能化导致吡啶氮原子处的电子密度显著增加，从而由于它们的+I-效应而导致其碱性显著增加。二氮杂硼基的胺氮原子是弱碱性的，可以作为半不稳定的供体官能团。计算表明，该配体体系可以稳定高活性的主基片段，如[SiCl]+的AlCl，并提供它们作为进一步的化学反应的电子。为了防止在吡啶的4-位的不希望的反应性，有必要用合适的官能团保护该位置。通过计算可以表明，具有+M-效应的取代基除了在2，6-位的取代基的+I-效应之外还进一步增加碱性。应证明（NacNac）M-（M = Zn，Mg）作为功能性高正电性基团在配体设计中的应用。阴离子吡啶配体在2，6-位被均三甲苯基取代，在4-位被三苯硼酸酯基取代的项目将通过一些总结性实验来完成。

The aim of this research proposal is the development of sterically and electronically modified pyridines as ligands for the stabilization of reactive main group element compounds. The functionalization of the 2,6-positions at the 2,6-Position of pyridine with electropositive diazaboryl groups results in a significant increase of the electron density at the pyridine’s nitrogen atom and thus to its basicity due to their +I-effect. The amine nitrogen atoms of the diazaboryl groups are weakly basic and can serve as hemilabile donor functions. Calculations show that this ligand system can stabilize highly reactive main group fragments like [SiCl]+ of AlCl and provide them as synthons for further chemical reactions. To prevent unwanted reactivities at the 4-position of the pyridine, it is necessary to protect the position with a suitable functional group. It could be shown by calculations that a substituent with a +M-Effect further increases the basicity additionally to the +I-effect of the substituents at the 2,6-positions. The application of (NacNac)M- (M = Zn, Mg) as a functional highly electropositive group in ligand design shall be demonstrated. The project with the anionic pyridine ligand substituted with mesityl-groups at the 2,6-positions and a triphenylborate-group at the 4-position, shall be completed with some concluding experiments.