Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany.
Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany.
Inorg Chem. 2021 Apr 5;60(7):5310-5321. doi: 10.1021/acs.inorgchem.1c00301. Epub 2021 Mar 5.
Dinuclear heteroleptic alkaline-earth-metal complexes are interesting synthetic targets because the close proximity of two metals allows for cooperative effects. However, these complexes are also prone to undergoing Schlenk-type rearrangements, affording less-active homoleptic complexes. Here we present the metalation of bis(β-diketimine) ligands possessing flexible bridging groups, i.e., 1,2-ethylene, 1,3-propylene, and -1,2-cyclohexylene, using calcium and magnesium precursors. Four mononuclear homoleptic calcium complexes were obtained, highlighting the pronounced tendency of calcium to undergo Schlenk-like redistributions. In the case of magnesium, however, the bridging group plays a crucial role, yielding seven dinuclear heteroleptic complexes but also one mononuclear and one dinuclear homoleptic complexes. In addition, a trinuclear mixed heteroleptic-homoleptic magnesium complex, which is a rare example of an intermediate of the Schlenk equilibrium, was isolated.
双核杂核碱土金属配合物是有趣的合成目标，因为两个金属的紧密接近允许协同效应。然而，这些配合物也容易发生施伦克型重排，形成不那么活跃的同核配合物。在这里，我们提出了使用钙和镁前体制备具有柔性桥接基团（即 1,2-乙烯、1,3-丙烯和-1,2-环己烯）的双（β-二酮亚胺）配体的金属化。得到了四个单核同核钙配合物，突出了钙经历施伦克样重排的明显趋势。然而，对于镁，桥接基团起着至关重要的作用，得到了七个双核杂核配合物，但也得到了一个单核和一个双核同核配合物。此外，还分离出了一种罕见的施伦克平衡中间体的三核混合杂核-同核镁配合物。
