Institut für Anorganische Chemie, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany.
Angew Chem Int Ed Engl. 2023 Feb 1;62(6):e202214599. doi: 10.1002/anie.202214599. Epub 2022 Dec 28.
Commercially available stock solutions of organolithium reagents are well-implemented tools in organic and organometallic chemistry. However, such solutions are inherently contaminated with lithium halide salts, which can complicate certain synthesis protocols and purification processes. Here, we report the isolation of chloride-free methyllithium employing K[N(SiMe ) ] as a halide-trapping reagent. The influence of distinct LiCl contaminations on the Li-NMR chemical shift is examined and their quantification demonstrated. The structural parameters of new chloride-free monomeric methyllithium complex [(Me TACN)LiCH ], ligated by an azacrown ether, are assessed by comparison with a halide-contaminated variant and monomeric lithium chloride [(Me TACN)LiCl], further emphasizing the effect of halide impurities.
市售的有机锂试剂储备溶液是有机和有机金属化学中很好的工具。然而，这些溶液中通常会含有卤化锂盐，这可能会使某些合成方案和纯化过程变得复杂。在这里，我们报告了使用 K[N(SiMe ) ]作为卤化物捕获试剂来分离无氯化物的甲基锂。我们考察了不同浓度的 LiCl 污染对 Li-NMR 化学位移的影响，并对其进行了定量分析。通过与受卤化物污染的变体和单体氯化锂[(Me TACN)LiCl]进行比较，评估了新的无氯化物单体甲基锂配合物[(Me TACN)LiCH ]的结构参数，该配合物由氮杂冠醚配位，进一步强调了卤化物杂质的影响。
