Kretsch Johannes, Kreyenschmidt Anne-Kathrin, Schillmöller Timo, Lõkov Märt, Herbst-Irmer Regine, Leito Ivo, Stalke Dietmar
Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstraße 4, 37077, Göttingen, Germany.
Institute of Chemistry, University of Tartu, Ravila 14a, 50411, Tartu, Estonia.
Chemistry. 2021 Jul 7;27(38):9858-9865. doi: 10.1002/chem.202100616. Epub 2021 May 25.
A novel sterically demanding bis(4-benzhydryl-benzoxazol-2-yl)methane ligand 6 ( BoxCH ) was gained in a straightforward six-step synthesis. Starting from this ligand monomeric [M( BoxCH)] (M=Na (7), K (8 )) and dimeric [{M( BoxCH)} ] (M=K (8 ), Rb (9), Cs (10)) alkali metal complexes were synthesised by deprotonation. Abstraction of the potassium ion of 8 by reaction with 18-crown-6 resulted in the solvent separated ion pair [{(THF) K@(18-crown-6)}{bis(4-benzhydryl-benzoxazol-2-yl)methanide}] (11), including the energetically favoured monoanionic (E,E)-( BoxCH) ligand. Further reaction of BoxCH with three equivalents KH and two equivalents 18-crown-6 yielded polymeric [{(THF) K@(18-crown-6)}{K@(18-crown-6)K( BoxCH)}] (n→∞) (12) containing a trianionic ligand. The neutral ligand and herein reported alkali complexes were characterised by single X-ray analyses identifying the latter as a promising precursor for low-valent main group complexes.
通过直接的六步合成得到了一种新型的空间位阻较大的双（4-二苯甲基-苯并恶唑-2-基）甲烷配体6（BoxCH）。从该配体出发，通过去质子化反应合成了单体[M(BoxCH)]（M = Na (7)，K (8)）和二聚体[{M(BoxCH)}₂]（M = K (8)，Rb (9)，Cs (10)）碱金属配合物。8与18-冠-6反应脱去钾离子，得到溶剂分隔离子对[{(THF)K@(18-冠-6)}{双（4-二苯甲基-苯并恶唑-2-基）甲烷化物}]（11），其中包含能量上更有利的单阴离子（E,E）-(BoxCH)配体。BoxCH与三当量KH和两当量18-冠-6进一步反应，生成了含有三阴离子配体的聚合物[{(THF)K@(18-冠-6)}{K@(18-冠-6)K(BoxCH)}] (n→∞)（12）。中性配体和本文报道的碱金属配合物通过单晶X射线分析进行了表征，结果表明后者是低价主族配合物的有前景的前体。
