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

本研究计划的目的是发展立体和电子修饰吡啶作为稳定活性主族元素化合物的配体。吡啶2,6位的2,6位与带正电的二氮硼基的官能化导致吡啶氮原子上的电子密度显著增加，从而由于它们的+ i效应而使其碱度增加。双氮硼基的胺氮原子是弱碱性的，可以作为半不稳定的供体功能。计算表明，该配体体系可以稳定AlCl的[SiCl]+等高活性主基片段，并为进一步的化学反应提供合成子。为了防止在吡啶的4位发生不良反应，有必要用合适的官能团保护该位置。计算表明，具有+ m效应的取代基除了具有2,6位取代基的+ i效应外，还会进一步增加碱度。（NacNac）M- (M = Zn, Mg)作为高正电官能团在配体设计中的应用将得到证明。阴离子吡啶配体在2,6位上被甲基亚取代，在4位上被三苯基硼酸取代的项目，应在完成一些结束性实验后完成。

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.